CNN  — 

President Donald Trump’s nomination of Amy Coney Barrett to the Supreme Court over the weekend is likely to further nationalize the fight for control of the Senate, with Republicans looking to defend a majority that was very much at stake well before Justice Ruth Bader Ginsburg died.

There’s no question the court battle has already injected more money and partisanship into many of these races, but a little more than week out from Ginsburg’s death, there isn’t yet enough data to definitively say whether the vacancy — another major national event in a year full of them — will benefit one party or another.

The loss of the liberal justice has been a fundraising bonanza for Democrats, many of whom already had significant financial advantages, with small-dollar donors giving more than $300 million via the online fundraising platform ActBlue since her death, according to a spokesperson. But it’s also stirring conservatives, who are hoping to remind right-leaning voters who may have soured on Trump of the importance of having a GOP-controlled Senate when it comes to the long-term balance of the high court.

The Senate landscape looks different from the last time there was a Supreme Court fight, just before the 2018 midterms. Two years ago, Democrats were on defense, and at least three of their red-state incumbents couldn’t overcome a highly partisan confirmation nationalizing their races.

This year, however, Democrats are on offense, defending just 12 seats to Republicans’ 23. Two of those Democrat-held seats — Alabama and Michigan — bookend this list of the seats most likely to flip partisan control, which was first published at the end of August. The remaining eight seats on the list are Republican-held. Democrats need a net gain of four seats to win control of the chamber, or three if Joe Biden wins the White House since the vice president breaks ties in the Senate. Inside Elections with Nathan L. Gonzales, a CNN contributor, rates six GOP-held seats either Toss-up or Tilt Democratic.

Interactive: 2020 Senate race ratings

Two of those are blue states that Hillary Clinton won in 2016, which is where Republicans fear a partisan Supreme Court debate could hurt the most. Democrats are already making Republicans’ push to confirm a new justice part of their advertising in Colorado – which maintains its spot at No. 2 – layering that message on top of their long-running attacks on the GOP on health care. The fate of the Affordable Care Act, a winning issue for Democrats in the 2018 midterms, has once again been thrust to the fore of the election, with the high court scheduled to hear arguments over the law the week after Election Day.

In Maine, another blue state where a Republican incumbent is facing a tough reelection, Democrat Sara Gideon is explicitly arguing that this election isn’t just about Sen. Susan Collins — who has said the Senate shouldn’t vote on a nominee before Election Day — it’s also about Majority Leader Mitch McConnell, whom the narrator in one of her recent spots says, is also on the ballot.

It’s possible Maine, which is No. 5 on the list, and North Carolina, which is No. 4, could soon switch places. If the Supreme Court vacancy does push voters deeper into their partisan corners, that could spell good news for North Carolina Sen. Thom Tillis, but bad news for Collins, who’s already alienated moderates and independents with her support for Justice Brett Kavanaugh in 2018 and isn’t likely to enamor herself with conservatives by saying a Trump nominee shouldn’t be confirmed before the election.

One change from late August: Montana is now ahead of Georgia in likelihood that it’ll flip control – largely because of candidate matchup and the uncertainty of a runoff in the Peach State – but a sustained Supreme Court fight could reverse that shift given that Montana is still a red state, while Georgia is looking increasingly purple.

Interactive: 2020 House race ratings

Kansas still does not make the list, but more than some of the other Democratic “reach seats,” the Sunflower State may deserve an honorable mention. Republican outside groups are continuing to have to spend money they should be spending elsewhere to boost the GOP nominee, who’s facing a former Republican. However, this is one of the red so-called firewall states where Republicans think their candidates will be boosted by increasing partisan feelings around the Supreme Court.

The bottom line: there’s plenty of speculation about how the struggle over the court will shape the race for the Senate, but it’s still too early to know how Ginsburg’s death is moving specific contests. That’s why CNN’s ranking of the top 10 Senate races remains largely unchanged since late August, when the political conventions had just ended and America was on the cusp of the traditional fall campaign season. A lot has happened since then — and undoubtedly a lot will happen between now and Election Day.

With just more than five weeks to go, here are the seats most likely to flip control:

1. Alabama

Incumbent: Democratic Sen. Doug Jones

senator doug jones convict trump vote 2

Jones maintains his spot as the most endangered senator — a position he isn’t likely to cede with the Supreme Court vacancy underscoring partisan lines in deep-red Alabama. But Jones isn’t running away from his party, most recently joining his fellow Senate Democrats in saying he’d oppose any Trump Supreme Court nominee before Election Day. He hasn’t shied away from going after Trump either, using the President’s alleged words about America’s fallen soldiers (and Fox News’ confirmation of parts of the account, first reported in The Atlantic) in an ad against Republican nominee Tommy Tuberville. Energizing the Democratic base, especially African-American voters, continues to be Jones’ most realistic path to victory. But while he’s enjoyed a financial advantage over Tuberville, it’s hard to see him overcoming the partisan bent of the state since he only narrowly defeated Roy Moore, who faced sexual assault allegations, in a 2017 special election.

2. Colorado

Incumbent: Republican Sen. Cory Gardner

02 Sen race rankings Cory Gardner

A nationalized race is the last thing Gardner wants in a state that voted for Clinton by about 5 points and where Trump is deeply unpopular. His opponent, former Democratic Gov. John Hickenlooper, launched one of the first ads to mention the Supreme Court vacancy, pointing out Gardner’s support for confirmation before the election. The first-term Republican is in a bind: he can’t afford to turn off the conservative base, but he’s also trying to hold onto enough ticket-splitting voters. He’s running ads touting his bipartisanship, and like many GOP incumbents this cycle, he’s been leaning into health care. But a recent Gardner spot that featured his mom, a cancer survivor, earned headlines for misleadingly saying his bill would “forever” guarantee protections for pre-existing conditions – even without Obamacare.

3. Arizona

Incumbent: Republican Sen. Martha McSally

03 Sen race rankings Martha McSally

Appointed to this seat after losing her 2018 Senate race, McSally faces a difficult path to victory in November that requires winning over Trump’s base and some of the suburbanites who dislike him. Unlike Gardner, though, she’s in a state where Trump is competitive, and there’s the chance that a tightening presidential race here – as one recent ABC/Washington Post poll showed – could boost her fortunes. But the Supreme Court fight could also underscore her liabilities with suburban women, whom she failed to win over in 2018. Democrat Mark Kelly, a former astronaut and the husband for former Rep. Gabrielle Giffords, doesn’t have a voting record and had a massive cash advantage as of mid-July, when the latest fundraising reports were available.

4. North Carolina

Incumbent: Republican Sen. Thom Tillis

04 Sen race rankings Thom Tillis

Trump has been holding a lot of rallies in North Carolina, which could be good news for first-term Sen. Thom Tillis, who’s struggled to consolidate the President’s base behind him. But when Trump makes news at those rallies, for example, by suggesting people to try to vote twice (which would be illegal), Tillis risks losing the well-educated and suburban voters who are making this state competitive up and down the ballot. Tillis’ allies have tried to turn some of the knocks against the President against Democrat Cal Cunningham, a former state senator and Army reservist, accusing him of being an “anti-vaxxer” because he said he’s concerned about political interference in public health. Cunningham, who outraised Tillis in the last quarter, has consistently led in public polling here but Republicans feel the race has tightened since Labor Day and that the stakes of the Supreme Court fight could bring home GOP voters to Tillis. There will be plenty more spending on both sides up until the end: North Carolina’s Senate race was the most expensive in the nation, with nearly $146 million in total ad spending, including what’s already been spent and future reservations, according to a CNN analysis of CMAG data as of September 21.

5. Maine

Incumbent: Republican Sen. Susan Collins

05 Sen race rankings Susan Collins

First elected in 1996, the Caribou, Maine, native has long relied on a moderate image to dispatch Democratic challengers. But Democrats’ central argument against her this year is that she’s no longer the senator Mainers have elected four times before. Collins’ vote for the 2017 GOP tax plan and contributions from the pharmaceutical industry have been especially prominent parts of Democratic messaging, although one recent spot from a Democratic outside group also spotlights her support for Supreme Court Justice Brett Kavanaugh. That 2018 vote was a rallying cry for moderate Republicans, independents and Democrats, particularly when it came to fundraising. Another Supreme Court vacancy allows Democratic state House Speaker Sara Gideon to argue that even if voters like Collins, they cannot afford to have another GOP vote in the Senate. At the same time, Collins’ refusal to confirm a Trump nominee before the election isn’t likely to win her any sympathies with the GOP base, whom she needs to turn out for her. One more complicating factor for Collins, who failed to hit 50% in several recent public polls, is ranked choice voting, which helped send New England’s last Republican member of the US House packing in 2018. She’s in a bind, but the question is if Gideon – who’s facing attacks on her record in the state legislature – can exploit it.

6. Iowa

Incumbent: Republican Sen. Joni Ernst