CNN  — 

Judging from earlier scandals, revelations about President Donald Trump’s deceit about coronavirus and derogation of fallen soldiers won’t repel many of his supporters.

But that doesn’t mean the revelations don’t hurt him. The furor they touched off has kept the President from tackling a re-election challenge much harder than preserving his loyal “base.”

With support hovering around 43% nationally, Trump needs a chunk of new supporters to overcome Democratic nominee Joe Biden’s lead. He has just more than seven weeks to lure them. And he faces a significant obstacle that he didn’t in 2016: a smaller pool of available prospects.

Outsized attention to Trump’s base, most conspicuously the maskless true-believers who pack his rallies despite the coronavirus pandemic, obscures the reality that they number too few to give him a second term. Though Trump eked out an electoral victory four years ago with 46.1% of the popular vote, he cannot repeat that feat with 43%.

The circumstances of 2020 limit his opportunities for several overlapping reasons:

Fewer voters remain undecided. That’s expected in a race between rivals as familiar as the incumbent and a former vice president. In CNN’s national poll after both major-party conventions, 13% of registered voters said they hadn’t chosen a candidate or could still change their mind. At the same point in 2016, that share of persuadable voters stood at 19%.

Fewer voters have parked their preferences with third-party candidates. In summer 2016, Libertarian standard-bearer Gary Johnson and Green Party nominee Jill Stein drew roughly 10% in combined support before fading to half that level by Election Day. Trump’s tumultuous presidency has diminished the market for experimentation, leaving comparatively-obscure third-party choices with smaller followings this year. NBC News/Wall Street Journal pollsters have found that third-party voters from 2016 now lean toward Biden.

Fewer voters face the cross-pressures of antipathy toward their choices. In 2016 exit polls, 18% of voters expressed negative views of both Trump and Hillary Clinton. They voted for him lopsidedly, tipping the election.

Most Americans still view Trump unfavorably. But fewer dislike Biden than felt that way about Clinton, the first-ever female major-party presidential nominee.

The result: in CNN’s post-convention poll, just 7% reported disliking both candidates. Most favored Biden.

View Trump and Biden head-to-head polling

Trump currently trails by 51%-43% nationally in CNN’s Poll of Polls, though more narrowly in decisive battleground states. But the shrunken persuadable pool makes those deficits more daunting.

“There’s less room for volatility,” says Democratic pollster Mark Mellman. “It is stickier.”

Intense feelings about Trump give Republican strategists reason to hope undecided voters might break his way. Anyone not against him already, they reason, may simply be seeking justification to back his re-election.

“Undecided voters tend to break away from the incumbent,” observes veteran Republican pollster Neil Newhouse. “In this case, it might be different.”

2020 vs. 2012

In fact, it was different when Newhouse advised Mitt Romney’s 2012 challenge to President Barack Obama. Voters who told exit pollsters they chose their candidate in October or later broke modestly in Obama’s favor.

Trump’s current standing means a modest break of undecideds won’t be enough. The President needs much more than that.

Election 2020: Send us your stories about voting issues

The vagaries of the Electoral College mean Biden could lose even while capturing 51% support nationally. Drawing within 3-4 points in the popular vote, election modelers say, would give Trump a reasonable chance.

But in individual swing states, anything over 50% wins. And Biden already reaches or approaches that level in enough battlegrounds to win.

In Wisconsin and Michigan, Biden cracked 50% support in averages calculated late last week by FiveThirtyEight; in Arizona and Pennsylvania, he drew 49.4% and 49.8%. If the former vice president can hold and augment that support with even a small share of undecideds, he’d capture 289 electoral votes – 19 more than needed to win.

Thus Trump needs “to claw back some people who now say they’re voting for Biden,” says Kyle Kondik of the University of Virginia’s Center for Politics. That won’t be easy.

The 2020 swing vote

Newhouse identifies potential targets: whites without college degrees and senior citizens. Biden, an avuncular presence with his own blue-collar appeal, has made inroads with both Trump-friendly constituencies amid the public health crisis and economic dislocation coronavirus has produced.

Trump seeks to reclaim lost white support with increasingly-raw appeals to racism, warning a Biden victory would “demolish the suburbs” through higher crime, expanded low-income housing, and untamed protests by the likes of Antifa and Black Lives Matter. But it’s unclear that voters even mildly drawn to Biden’s more unifying message will find that plausible or appealing.

In a Pew Research Center survey last month, 11% of current Biden supporters called themselves only “leaning” his way. Among that group, 93% disapproved of Trump’s performance as President.

The burden of proof Trump faces underscores his recent lost opportunity. As Trump fended off media bombshells, he didn’t lose national support but didn’t gain any, either.

And with early voting already underway in some places, the calendar kept moving.

“Even if he closes strong, fewer undecideds just means it’s harder to close that gap,” notes John Sides, a Vanderbilt University political scientist. “With every passing week, there’s just less and less than can move the needle.”