CBS News Biden-Trump poll finds concerns about Biden finishing a second term, and voters' finances also weigh on Biden

John Avlon: Joe Biden is down one point in a match-up with Donald Trump , whom he beat by seven million votes three years ago .

He says voters are unsure he'd stay through a second term if he did get one, adding uncertainty to an already unsettled public.

Voters are more likely to think only Trump — and not Mr. Biden — is physically healthy enough for the job, Avlon says.

Democratic efforts to try to portray the Republicans as too extreme don't seem to be playing to Democratic advantage because Democrats are described by just as many as extreme.

People who think the Democrats go too far on racial diversity and equality also describe the Democratic Party as "extreme," more generally.

Biden may be disadvantaged because key parts of his 2020 coalition aren't as tuned in to the campaign yet.