Former U.S. President Donald Trump attends a rally to support Republican candidates ahead of midterm elections, in Dayton, Ohio, U.S. November 7, 2022.
CNN  — 

The powerful evidence for a possible criminal case that the bipartisan January 6, 2021, congressional committee presented against former President Donald Trump on Monday underscores the biggest uncertainty looming over the approaching 2024 presidential campaign.

Many factors that will shape the 2024 contest, of course, remain impossible to know almost two years before the voting. But it is possible with greater confidence to identify the questions whose eventual answers will exert the most impact on the result.

During the Iraq War in 2002, Donald Rumsfeld, then the defense secretary, coined a famous phrase to describe exactly that kind of situation. Rumsfeld puckishly described a circumstance in which we do not know the answer to a question, but we do know that the answer will matter to the outcome, as a “known unknown.”

Whether the GOP nominates Trump again in its 2024 presidential primaries – a dynamic that in turn will be powerfully influenced by whether he faces a criminal indictment and how GOP voters react if he does – looms, in my view, as the most important “known unknown” for 2024.

That’s not the only important “known unknown” likely to influence 2024, though. Presidential races have become such vast and encompassing competitions that a list of such “known unknowns” could stretch indefinitely. What I’ve done below is try to identify five that, at this point, appear that they could be the most significant. I’ve ranked them in rough order of my estimation of their likely impact on the eventual outcome. And they begin with the fateful decision about Trump hurtling toward the GOP.

1. How does the Republican nomination fight play out? If Republicans nominate Trump again in 2024, no other factor on this list may matter much. For many voters, such an election might reduce to a binary choice: whether or not they would again entrust Trump with control over the federal government. Democrats are confident enough of the answer that most are rooting for Trump to win the nomination.

Trump’s strengths and weaknesses in the 2024 GOP nomination fight, in key respects, resembles his situation in 2016: now, as then, he’s facing resistance from most Republicans with at least a four-year college degree, but polling well among Republicans without one. One key difference from 2016 is that more of the party elite – including elected officials and fundraisers – are openly resisting Trump, fearing that Democrats are right in their prevailing belief he cannot win again. Partially for that reason, Florida Gov. Ron DeSantis, if he runs, may be better positioned than any of Trump’s 2016 rivals to consolidate the GOP voters skeptical of him (though he’s hardly guaranteed of success in that).

The possibility that Trump could face a criminal indictment – either on the evidence the January 6 committee detailed on Monday or separate investigations from the Justice Department on his stockpiling of classified documents and the Fulton County, Georgia, district attorney on his efforts to overturn the election there – adds another new wrinkle. Veteran conservative strategist Bill Kristol, now a staunch Trump critic, says he initially worried that a backlash from rank-and-file GOP voters against any indictment might boost Trump; now Kristol believes it will only compound the sense he carries too much baggage to win another general election.

If DeSantis or another alternative beats Trump, the GOP will confront a pair of bookended risks. One is that Trump openly disparages and undermines the eventual nominee – in the most extreme case by launching a third-party general election bid. The other is that the eventual winner beats Trump only by, in effect, out-Trumping him in on culture war issues such as abortion, LGBTQ rights, gun control, immigration, the coronavirus response and other issues. (DeSantis has already given indications he may pursue that strategy.) That could leave the nominee little (if any) more marketable than Trump himself in the white-collar suburbs from Pennsylvania to Arizona that have trended sharply away from the GOP since his emergence.

2. How do voters assess the economy? Democrats defied history in 2022 by running unexpectedly well even though about three-fourths of voters expressed negative views about the economy, according to exit polls. But that’s not an experiment any Democrat would want to repeat in 2024.

Voter attitudes about the economy in 2024 will likely hinge on their reaction to the trade-off the Federal Reserve Board is imposing through its repeated interest rate hikes: lower inflation for higher unemployment and less growth. At its December meeting, the Fed forecast that inflation would ease significantly in 2023 (and decline further through 2024) but unemployment would tick up to 4.6% across both years and overall economic growth would slow sharply enough to leave the economy on the edge of recession through next year.

There’s some evidence more Americans would prefer that to the opposite conditions that have prevailed over the past two years: robust growth and an extremely strong job market coupled with the highest inflation in four decades. In a CBS poll earlier this year, far more adults cited inflation and high gas prices than the unemployment rate as the reason they were unhappy about the economy. “Something approaching 100% of the electorate experiences the high cost of living and a much smaller fraction experiences unemployment or even job insecurity at any given time,” says Geoff Garin, a veteran Democratic pollster and strategist. “So, if you had to pick your poison, an economy with a lower cost of living and a slightly higher rate of unemployment, is probably more manageable.”

Still, that’s not guaranteed: when an October CNBC poll asked directly whether the Fed should prioritize reducing inflation or protecting jobs, a slight plurality picked the latter. In any case, almost all political analysts agree that more important to the election’s outcome than the absolute level of those economic indicators will be whether they are improving or deteriorating, particularly in the spring and summer of the election year, when many voters lock in their verdict on the economy. The classic example came in 1984, when Ronald Reagan’s 49 state landslide was fueled by a rapid decline in unemployment, even though it still exceeded 7% on Election Day.

3. Do voters consider Biden still up to the job? Before the midterm election, the key question surrounding Joe Biden might have been whether he would face a serious primary challenge, which often has foreshadowed defeat for an incumbent president. But the Democrats’ relatively strong showing in the midterm has virtually eliminated that possibility and left the president “very clearly in a pretty good place” within the party, notes Garin.

Yet, despite the Democrats’ unexpectedly strong performance, the midterms showed warning signs for Biden among the broader electorate: a solid majority in the exit polls said they disapproved of his job performance, and two-thirds of voters said they did not want him to run again.

Reagan, Bill Clinton and Barack Obama, three other presidents who faced widespread discontent early in their presidencies, saw their approval rating rise as they neared reelection when attitudes about the economy improved. If inflation recedes, that same current could lift Biden (whose approval rating already has ticked up since his party’s midterm showing). What’s unknown is how many voters, even if they feel better about the economy, still will consider Biden too old (he’ll turn 82 shortly after the 2024 election) or diminished for the office. Any visible health problem between now and then would obviously exacerbate those concerns.

Most Americans now appear to view elections for the White House and Congress less as a choice between two individuals than between which party they want to set the nation’s direction, a dynamic that will limit the political impact of judgments about Biden’s personal capacity. But, even in such an increasingly parliamentary environment, Biden will likely need to convince a critical slice of swing voters that he can effectively perform the job before they reelect him to it.

4. Can either party reverse the electoral trends benefiting the other? On balance, the 2022 election reaffirmed the basic lines of demographic and geographic division between the parties evident in the 2020 results.

Relative to 2020, the Democrats’ performance eroded at least somewhat among most key groups – not surprisingly in a midterm while they held the White House, especially against the backdrop of a four-decade high in inflation. But, overall, the party mostly preserved the same coalition of voters who turned out in decisive numbers to oppose Trump in 2018 and 2020 – young people, people of color, college-educated White voters, secular and LGBTQ adults, and residents of the largest metropolitan areas, with women in each group usually leaning more markedly toward them.

Behind that coalition, Democrats beat every Trump-backed Senate and gubernatorial candidate in the five states that decided the 2020 election by flipping to Biden after backing Trump in 2016: Michigan, Pennsylvania, Wisconsin, Arizona and Georgia. Those winning Democratic candidates all prevailed by bigger margins than Biden did two years earlier – a stunning divergence from the usual pattern of the president’s party losing ground in midterms.

Those results suggest the shift of white-collar suburbs in those states away from the GOP means Democrats enter 2024 with an edge, though not an insurmountable one, in the Electoral College. The other good news for Democrats: Millennials and Generation Z, who continued to back them in large numbers, will comprise well over-two-fifths of eligible voters in 2024 and likely, for the first time, exceed the baby boom and older generations among actual voters, according to calculations by the non-partisan States of Change Project. “The Republicans really are talking to an older shrinking population,” says Brookings Metro demographer William Frey, who helped calculate those projections. “It is still big in a lot of places, but it is now being countered by this youthful and more diverse population and they are going to pay a price if they don’t adjust their policies and messaging.”

The key demographic unknown for Democrats may be whether they can continue to inspire the relatively higher turnout among the younger generations that have boosted them over the past three elections. The key unknown for Republicans in 2024 may be whether they can regain ground in the well-educated and racially diversifying suburbs of the five Trump-to-Biden states.

Some Republican strategists see a model in Georgia Gov. Brian Kemp’s relatively stronger performance in the Atlanta suburbs after a term in which he advanced a staunchly conservative agenda (including signing a six-week abortion ban) but demonstrated his independence by rejecting Trump’s efforts to overturn the 2020 election there. Georgia showed that the suburban voters now rejecting the Trump-stamped GOP “can go back and forth depending on the quality of the candidate and the kind of campaign they run,” says long-time GOP pollster Whit Ayres.

5. Does the Republican-majority House do more damage to Biden – or to the GOP? The incoming GOP majority has already set a confrontational course toward Biden. It has promised an array of investigations (starting with the business activities of his son, Hunter Biden, and potentially including the treatment of the January 6 insurrectionists), warned that it may impeach Department of Homeland Security Secretary Alejandro Mayorkas (as well as possibly other officials) and already laid plans to threaten a default on the federal debt to demand cuts in federal spending, including potentially Social Security and Medicare.

These are all causes that could energize the GOP base for 2024. And a sweeping dragnet of House investigations might unearth uncomfortable revelations for the Biden Administration about its handling of the border, its dispersal of funds from the infrastructure and climate change bills, or other issues.

But Democrats are strikingly confident that on balance the narrow GOP House majority will do more damage to the Republican brand by instigating political fights distant from the daily concerns of most Americans and by elevating divisive figures like Reps. Marjorie Taylor Greene of Georgia and Jim Jordan of Ohio who are poised to reinforce the image of Trump-affiliated extremism that hurt Republicans in 2022. Simon Rosenberg, the Democratic strategist who was the most prominent public skeptic of the “red wave” theory in 2022, previewed that line of attack on Monday when he tweeted a list of controversies swirling around Trump and the Republican Party and declared: “GOP all MAGA, all the time.”

Other “known unknowns” could send ripples through the 2024 campaign-including a decisive outcome (that favors either side) in the Ukraine war, Supreme Court decisions on election rules and the crime trends in major cities. And even these prospects don’t exclude what Rumsfeld called the “unknown unknowns” – the possibilities “we don’t know [that] we don’t know,” as he put it then. Uncertainty is unavoidable in a contest as consuming as a modern presidential race. But, even so, I wouldn’t be surprised if the outcome of the five “known unknowns” listed above decide the outcome.