Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE’s ability to inspire voters is under scrutiny as the presidential campaign reaches its most critical phase.

Voter enthusiasm is essential for both parties, but especially for Democrats, who have long maintained they win if turnout is high in a presidential election year. If Clinton’s numbers don’t improve in this critical area, she could lose on Nov. 8.

ADVERTISEMENT

The Democrat’s once-comfortable lead in the polls has tightened considerably. Democrats were startled on Tuesday by a new CNN/ORC poll that gave GOP nominee Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE a 2-point lead nationally.

The CNN poll also suggested that Clinton backers are less enthusiastic in their support for their candidate than are their Republican counterparts.

Fifty-eight percent of those who backed Trump said they were “extremely enthusiastic” or “very enthusiastic” about doing so, compared to 46 percent of Clinton supporters who felt the same way about the former secretary of State.

At the other end of the spectrum, more than 1 in 5 Clinton supporters, 21 percent, were “not at all enthusiastic” about the candidate. The corresponding number among would-be Trump voters was just 11 percent.

The poll reawakened fears among Democrats that Clinton’s vulnerabilities, as well as the sheer length of time she has been on the political scene, may leave her struggling to appeal to a restive electorate unhappy with the Washington establishment.

President Obama’s capacity to engender enthusiasm from nonwhites, young people, liberals and college-educated whites was central to his two electoral successes.

The evidence is mixed as to whether Clinton can hold the Obama coalition together and spark turnout at similarly high levels. In her primary battle with Sen. Bernie Sanders Bernie SandersJacobin editor: Primarying Schumer would force him to fight Trump's SCOTUS nominee Trump campaign plays up Biden's skills ahead of Cleveland debate: 'He's actually quite good' Young voters backing Biden by 2:1 margin: poll MORE (I-Vt.), she ran up huge margins among black voters but struggled mightily with young people.

“Hillary Clinton really has to motivate the young voters to turn up, and their lukewarm-ness is pretty evident,” said Susan MacManus, a professor of government at the University of South Florida.

MacManus based that assertion not just on polls but also on her own observations on campus.

“In 2012, and certainly in 2008, there was overwhelming and enthusiastic support for Obama. I’m not seeing that,” she said.

But MacManus also noted that Trump has his own challenges with turnout and voter enthusiasm given his tumultuous path to the Republican nomination and misgivings among some conservatives as to whether he is really “one of them.”

Evidence of GOP resistance to Trump has been plentiful, including Texas Sen. Ted Cruz Rafael (Ted) Edward CruzThe Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy Murkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight MORE’s dramatic speech at the Republican National Convention, in which he declined to endorse the nominee; the comparatively strong performance in polls of the Libertarian Party’s Gary Johnson Gary Earl JohnsonWhat the numbers say about Trump's chances at reelection Presidential race tightens in Minnesota as Trump plows resources into state The Hill's Campaign Report: Biden condemns violence, blames Trump for fomenting it l Bitter Mass. primaries reach the end l Super PAC spending set to explode MORE; and the presidential candidacy of former House GOP staffer Evan Macmillan, which is expressly aimed at attracting disaffected Republicans.

Trump and Clinton have higher unfavorable ratings than any major party nominees of modern times. For the moment, Trump performs worse in most polls by that measure.

That, in turn, is giving Democrats some comfort. Voters will go to the polls for Clinton, they hope — even if a large part of their motivation is keeping the GOP nominee out of the White House.

“When you look at the negatives of both of these people, there is no enthusiasm except for people who dislike the other one more,” said Hank Sheinkopf, a Democratic strategist who has worked with Clinton but is not doing so in this campaign.

“The question is: How do you translate the dislike of the other one into turnout? Secretary Clinton’s job is to make Trump more unacceptable.”

Clinton is making that case right now. On Tuesday, she accused her opponent of involvement in “the scams, the frauds, the questionable relationships, the business activities that have stiffed workers.”

The best-known Clinton ad of the cycle features footage of young children watching Trump making some of his most incendiary remarks. The spot clearly aims to paint the Manhattan businessman as lacking in basic decency.

Other Democrats note that Clinton has significant advantages over Trump in terms of campaign infrastructure. The number of field offices she has in battleground states easily exceeds Trump’s: the tally stood at 291 to 88 at the end of August, according to a recent “PBS NewsHour” analysis. The sophistication of her campaign’s data analytics operation could also help her to get out her vote.

“I have plenty of criticisms [of Clinton] but not on this,” said Jim Manley, a former aide to Senate Democratic Leader Harry Reid Harry Mason ReidOn The Trail: Battle over Ginsburg replacement threatens to break Senate Democrats fear Russia interference could spoil bid to retake Senate Graham signals support for confirming a Supreme Court nominee this year MORE (Nev.). “I think it is going to become evident that she has a very effective get-out-the-vote operation and that could make the difference. Trump, after all, doesn’t have any of this stuff.”

Almost all experts agree that Clinton is so well-known that she cannot suddenly win over blocs of voters.

Her path to victory, they suggest, lies partly in the practical strengths that Manley outlined — and in making a campaign that is already negative even more so.

“Unless there is some extraordinary event that occurs, this will be a slog from now until the end,” said Sheinkopf. “What each of those candidates is trying to do to diminish the other. It’s not about who is the nicer person. It’s about who is less acceptable.”