It's been widely observed that Biden is doing quite a bit better than Clinton among older voters (65+). Ron Brownstein:
"Biden led Trump among seniors comfortably in recent general election polling by CNN, Quinnipiac and NBC/WSJ and more narrowly in the latest Monmouth University poll. Though Pew and Grinnell College in recent polls still showed Trump leading with seniors, the overall direction of the surveys suggests that Biden might significantly improve on the Democrats' recent performance among older voters. Each Democratic presidential nominee since John Kerry in 2004 has lost seniors, a preponderantly white age cohort, by at least 5 percentage points, according to exit polls; Al Gore in 2000 was the last Democrat to carry them."
My analysis of the Nationscape survey (UCLA/Lucid//Democracy Fund Voter Study Group; over 70,000 cases since the beginning of the year) confirms this pattern. I find that Biden is leading Trump by 4 points on average among 65+ voters. That compares to Clinton's substantial deficits among this group in 2016, according to the two best data sources about the election, States of Change and Catalist. States of Change has Clinton at -15 among seniors, while Catalist makes it -14.
That's quite a large swing. Of course, many nervous Democrats fear Biden will lose those gains--if he even gets them--among younger voters. They fear a repeat of Clinton's poor performance among these voters in 2016.
But that's really a bit of a myth. The fact of the matter is that Clinton did about as well as Obama did among this group in 2012. That was not her problem. The Catalist data show the share of younger voters (18-29) identical (14 percent) across the two elections, while the Democratic margin was also essentially the same (+25 in 2016; +26 in 2012). The States of Change data show The States of Change data show youth voter share going up slightly from 15 percent in 2012 to 16 percent in 2016, with the youth turnout rate having the largest turnout increase of any age group. And the youth Democratic margin was identical across the two elections (+27).
Given what is happening with senior voters, it would take a catastrophic decline in Democratic margin among young voters to cancel that out. We're not seeing it so far. The Nationscape data have that margin at an average of 22 points; the recent Harvard/Institute of Politics survey specifically of young voters has Biden's margin at +23 among those registered to vote and +30 among those deemed likely to vote.
Given that the size of the senior vote should be around 24-25 percent of the electorate in 2020, compared to 14-16 percent among young voters, that's a trade-off you'll make every day. If it even winds up being a trade-off, about which I have my doubts.