Clinton's big worry

Story highlights

  • Democrats should fear Trump and anticipate a campaign that is much tougher than they are expecting, says Julian Zelizer
  • Trump has proven far more effective in the campaign thus far than predicted, and Clinton has issues, he says

Julian Zelizer is a professor of history and public affairs at Princeton University and a New America fellow. He is the author of "Jimmy Carter" and "The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society." The opinions expressed in this commentary are his.

(CNN)There are many reasons why Democrats should feel good about the election now that Donald Trump is the Republican nominee. Even before GOP voters went for Trump, the Electoral College math tended to favor the Democrats. Republicans will be playing catch up.

Trump has also deeply divided the Republican Party, with many of the most prominent leaders refusing to endorse him. Usually when parties divide this badly they lose.
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    Unlike almost any other Republican in the current age of polarization, Trump has the potential to generate a backlash of Republican voters against their own party, causing them to either stay home on Election Day or, even worse for the party, consider voting for the Democratic nominee.
    Yet with all of these advantages, Democrats should be extremely careful about becoming overconfident. There are many reasons that Democrats should fear Trump and anticipate a campaign that is much closer and much tougher than they are expecting.
    The Electoral College can be much more fluid than most commentators have argued. Yes, Democrats have an advantage, but that advantage can be broken. Nate Silver and Jonathan Bernstein have both written about how these predictions overstate how inevitable the outlook looks for the fall.
    While swing states have gone to Democrats in most recent elections, if the Republicans have a good year those swing states could easily shift in a different direction. Bernstein also points out that individual states like West Virginia have undergone very big shifts. (A poll released Tuesday showed close match-ups between Clinton and Trump in three swing states.)

    What we don't know

    Given the instability we have seen in the electorate, especially in states hard hit by economic challenges, this could be the case in 2016. There have been numerous examples, such as the Election of 1992, when the electoral hold of a party suddenly came undone. We have already seen in the primaries that the electorate is much more unpredictable than many experts anticipated.
    Added to this is the historical precedent that a party rarely wins a third straight term in the White House. And Trump is such an unusual candidate it is difficult to know how this will play out.
    How Trump will do in a general election campaign is also unknown. Predictions about his candidacy are almost impossible to make. We should remember that just a few months ago, most of the major experts were predicting that a Trump nomination was virtually impossible.
    Now that he will be nominated, they are shifting to predictions that a Trump general election victory will be impossible. Next, they might find themselves predicting that his reelection will never happen.
    The point is that we don't really know what his candidacy will look like or how it will play out. He has already demonstrated that his campaign is different. His unorthodox blend of policies, his mastery of the modern media, and his ability to tap into the anger and frustration of the electorate have moved voters in a different direction.

    Tapping into unrest

    With his attacks on free trade he has tapped into clear unrest in key states, like Ohio and Pennsylvania, that could attract Democratic voters. Trump will also do more than any other candidate would have done to drive up underlying animosity that exists about voting for a female candidate.
    If he can cut into independent votes and even some Democratic constituencies in blue states like Pennsylvania, he might be more threatening than expected. We also don't know how honest voters have been to pollsters about whether they would vote for him. It is possible some people are not comfortable admitting that they would give him their support.
    Trump has mastered the news media and he won't let up. Candidates who are skilled at working in the media environment of their time (think about how Jimmy Carter sold his insurgent campaign to the post-Watergate generation of reporters in 1976) can have a powerful effect on what actually happens. As Dave Roberts argued in Vox, this can lead reporters to downplay certain aspects of Trump's candidacy.
    And while it is true that there have been a number of high-profile defections among Republican leaders in recent days, it is far too early to conclude that the party will be split. After all there will be equally strong political pressure for Republicans to fall in line behind their candidate, with the potential for a Democratic president and a Democratic Congress being much more frightening to them than a maverick from within their own party.
    Nor is it yet clear that the defections among leaders will be followed by defections in the electorate. This certainly could happen, and a electoral backlash against the GOP is a very real possibility in 2016, just as it was when Republicans nominated Barry Goldwater in 1964.
    This could leave Democrats with control of the White House, Senate and House -- and with a huge window for legislating. But it also could play out differently. Given the anti-establishment mentality that exists right now, political leaders saying that they are against Trump might just lead more voters to support him.

    Clinton's stumbles

    There are also many reasons for Democrats to worry about Hillary Clinton. She has proven herself again and again to be vulnerable. With all of her campaign experience and with all of her immense political skill, we have seen time and time again how she and her team can stumble badly, like when she said in June that she and her husband were "dead broke" when leaving the White House, a comment that didn't sit well with many Americans who struggle every day to survive.
    Nobody expected a 74-year-old socialist from Vermont to mount a serious challenge to her candidacy. But Bernie Sanders did. Whether it's the Goldman Sachs speeches or the e-mail server issue, we have also seen how Clinton often has trouble responding to the kind of scandal warfare that is an inevitable part of the political system, frequently allowing small issues to get blown up into much bigger controversies. Her disapproval ratings are very high -- though not as high as Trump's -- and one never knows what kind of trouble Bill Clinton might bring her campaign.
    In a recent column the Washington Post's E.J. Dionne, one of the most astute political commentators of our time, confessed: "Never again will I underestimate Trump, having done this a month ago, rashly predicting he would lose the Republican nomination. I clearly had an excess of confidence that Cruz could rally anti-Trump voters and thought a series of wildly outrageous Trump statements would do more harm to his candidacy than they did. I was dead wrong as a pundit, allowing myself to get carried away by my confidence that, at the end of it all Americans would see through Trump."
    More Democrats and more experts should take Dionne seriously. This does not mean that Trump doesn't face enormous obstacles and that his candidacy might not still produce the disastrous effects for the GOP that some foresee on the horizon. But there should be some more sober perspectives on predictions for the fall. The truth is we don't know what we are in for, and Democrats should not be overly confident about this race being a slam dunk.