(CNN) President Joe Biden won the 2020 election in large part because he was able to win the center. He emerged with a 13-point win with independent voters, a group that Democratic presidential nominee Hillary Clinton lost by 4 points in 2016. (House Democratic candidates, for their part, took independents by 9 points in 2020.)
That's why it should be alarming to Biden that the recent downturn in his approval rating has come disproportionately from independents, as the Washington Post's Henry Olsen first pointed out. This slide could have major electoral implications, if it holds.
You can see this trend among independents in polls that meet CNN's standards for reporting. Biden's net approval rating (approve-disapprove) among independents in polls completed in September and October stands at -16 points. Not surprisingly, his net approval rating is significantly higher among Democrats (+79 points) and lower among Republicans (-84 points).
Biden's net approval rating was better among all groups in an average of polls back in June and July. His net approval rating stood at +88 points among Democrats, +3 points with independents and -72 points among Republicans.
The key thing here though is that while the drop among Democrats (9 points) and Republicans (12 points) is evident, it's even larger among independents (19 points).
In some ways Biden's disproportionate decline with independents shouldn't be surprising. If you are less attached to a political party (which independents are as a group), you're more likely to swing.
Additionally, the 2020 results with independents may have been more a reflection of displeasure with then-President Donald Trump than admiration for Biden. A dig into the exit polls reveals that even though Biden beat Trump among independents by 13 points, his own net favorability rating (favorable - unfavorable) was just +6 points with them. Trump's, meanwhile, was -18 points.
Biden's net approval is now basically where Trump's popularity was with independents on Election Day 2020.
With Trump out of the picture, Biden's now standing on his own record -- one that a lot of independents seem less than impressed with.
According to an NBC News poll finished in the back half of August, just 32% of independents (including those who say they lean towards the Democratic or Republican party) and 38% of pure independents (those who don't lean) say Biden has accomplished a great or fair deal in office. The vast majority (64% among all independents and 59% among those who don't lean towards a party) say he's done only some to very little in office.
Looking forward, Biden's standing with independents may be helped if two signature pieces of legislation become law.
Independents -- by a 57% to 27% margin -- favor the $1.2 trillion infrastructure deal already passed by the Senate, according to an average of recent Pew Research Center and Quinnipiac University polls.
They're more split (48% support vs. 37% opposed) on the $3.5 trillion package for social programs for child care and expanding medicare among other things. Still, even here support among independents vastly outstrips Biden's own standing with them.
If Biden doesn't do something to change his numbers with independents, it's not out of the question that his party could suffer at the polls.
An examination of history reveals that independents can change their mind pretty quickly on how they vote in-between presidential and midterm elections. We can see this in three of the biggest wave elections in recent memory: 1994, 2010 and 2018.
From 1992 to 1994, independents switched from favoring House Democratic candidates by 8 points to voting for Republicans by 14 points.
From 2008 to 2010, they went from going for Democrats by 8 points to Republicans by 18 points.
From 2016 to 2018, they went the other way from voting for House Republican candidates by 6 points to backing Democrats by 12 points.
The shift in independent voters in all these elections was larger than among members of either major party.
Of course, it's important to keep in mind that Republicans don't need a massive shift in voter opinion to do well in the midterms. Democrats have only the slimmest of majorities in the House and Senate.
Those majorities are very much in danger right now.