Roughly three months before Election Day, a new poll from the Associated Press-NORC Center for Public Affairs Research finds Joe Biden’s supporters are less enthusiastic than President Donald Trump’s, both about the campaign itself and about their candidate.

But the presumptive Democratic White House nominee’s coalition may be equally motivated by anxiety.

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The AP-NORC poll of 1,057 adults, including 922 registered voters, was conducted July 16-20 using a sample drawn from NORC’s probability-based AmeriSpeak Panel, which is designed to be representative of the U.S. population. Its margin of sampling error is plus-minus 4.3 percentage points.

The poll reveals an American public at odds with Trump on wearing masks, on balancing restrictions to stop the virus with efforts to help the economy and on fully reopening schools. And voters give Biden higher marks on many positive traits that apply to leadership in the age of the coronavirus, including honesty, capability and caring for Americans.

Just 31 percent of Biden supporters say they’re excited, compared with 42 percent of Trump supporters. Biden’s coalition is fueled by more negative emotions: 72 percent of Biden supporters, but 52 percent of Trump supporters, say they feel anxious about the 2020 campaign.

The same disparity exists for frustration with the election, 65 percent for Biden supporters and 45 percent for Trump’s.

This past Saturday marked 100 days until the Nov. 3 election. A recent ABC News analysis showed Biden with a slight Electoral College lead over Trump, with 279 electoral votes solidly or leaning Democratic. Another 72 electoral votes are rated as toss-ups, while 187 are either solid or leaning Republican.

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Biden’s campaign dismisses the idea of an enthusiasm gap. It says that with Trump’s level of support shrinking, a greater share of energized supporters is left behind in the diminished pool. Trump’s job approval in the new poll sits at 38 percent.

Just 32 percent of voters approve of the way Trump is handling the pandemic, a low point that follows a steady decline from the outset of the crisis. While Trump’s supporters almost unanimously approve of his performance overall, 2 in 10 disapprove of his response to the pandemic.

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The poll also found voters generally prefer Biden’s character and values. About 6 in 10 registered voters say that values like “cares about people like you,” “honest” and “strong leader” do not describe Trump well. By comparison, roughly the same majority say those characteristics describe Biden at least somewhat well.

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And in considering whether the two are "capable" — a question that likely reflects voters' views of each man's mental acuity and ability to govern — fewer say that describes Trump than Biden at least somewhat well, 43% vs. 56%. Trump, who's 74, and his allies have made attacks against Biden's age and cognitive ability a centerpiece of their message.

Trump has an advantage on standing up for what he believes. Seventy percent think this describes Trump at least somewhat well, including 54% who think it describes him very well. Sixty-three percent think standing up for his beliefs describes Biden at least somewhat well, but just 36% think it describes him very well.

Trump’s supporters are much stronger in their positive descriptions of Trump than Biden backers are of their candidate. For example, wide majorities of Trump supporters think “stands up for what he believes” (87 percent), “strong leader” (75 percent) and “capable” (76 percent) describe the president very well.

Fewer Biden supporters think “standing up for what he believes” (63 percent), “strong leader” (50 percent) and “capable” (56 percent) describe Biden very well.

For Biden, a significant age gap within his coalition drives the lukewarm ratings. Older Biden supporters are much more likely than those under 45 to say such traits describe Biden very well.

The Associated Press contributed to this report.