(CNN) — Black voters form the core of the Democratic Party base. They cast ballots for Democrats in greater proportions than pretty much any other demographic group. Without the massive backing of Black voters, the last three Democratic nominees (Joe Biden, Hillary Clinton and Barack Obama) would not have made it to the general election.

Yet, recent polling suggests the advantage Democrats have had with Black voters may be slipping, at least a little bit. This follows the 2020 election in which Biden won Black voters by less than 80 points — the weakest margin for a Democratic presidential nominee since 1996 (if your baseline is the network exit polls).

A few weeks ago, Gallup released results comparing Biden’s approval rating since October with the first six months of his administration. Much attention has been paid to his 20-plus-point drops with young adults and Hispanics.

Far less noted was that Biden’s approval rating among Black adults stood at a mere 67%. That was down 20 points, from 87% at the beginning of his presidency, which was fairly in line with the percentage of Black voters who backed him in 2020.

To put this in context, Obama’s approval rating with Black adults never dropped below 75% in any individual Gallup poll. Averaged across time, it almost always stayed safely above 80%.

Perhaps, it was the fact that Biden’s approval rating with Black adults remains high when compared with other groups that the 20-point decline didn’t get much notice. Regardless, the Gallup poll is hardly alone.

Our most recent CNN/SSRS poll on the subject found Biden’s approval with Black adults was 69%. It stood at 74% with Black voters. A recent Quinnipiac University poll put Biden’s approval rating with Black adults at 64%. A Pew Research Center poll last month had him at 72% among Black voters.

All these polls showed Biden losing a disproportionate amount of support from Black adults (and voters).

Of course, a president losing support with a group doesn’t necessarily translate to changes in electoral preferences. Biden may be down with younger voters, but, as I’ve noted, their midterm preferences should not be drastically different from how they voted in 2020, even considering the current national environment for Democrats.

An examination of the generic congressional ballot indicates, though, that Black voters, at this point, seem far less likely to vote Democratic than you might expect given their voting history.

Take a look at an average of polls — from CNN, Fox, Quinnipiac and Pew — over the last few months. Democrats have a 62-point lead among Black voters, 73% to 11%. That may seem large, but it’s small from a historical standpoint.

The 2020 network exit polls had Democrats winning the national House vote among Black voters by 75 points (87% to 12%). The data firm Catalist calculated that Democrats won by 79 points (89% to 10%). Averaged together, Black voters went Democratic by a 77-point margin in the 2020 House vote.

What current polls indicate is a 15-point decline from that margin among Black voters. For comparison, among Hispanic voters, Democrats are down 5 points from their 2020 House margin.

You’d have to go all the way back to 1990 to find any year, at least according to the exit polls, in which Democrats won the national House vote among Black voters by as little as their lead in the current polls.

When ideology aligns with voting patterns

While Democrats are doing worse among Black voters compared with 2020, Republicans aren’t doing better. Things can change as we get closer to November, and Democrats could gain back some of the ground they have lost.

But there’s plenty of room for Democrats to fall from their 2020 baseline, given the trends of the last two presidential elections. Unlike in most other demographic groups, Black voters who identify as conservative have historically been quite Democratic. Hillary Clinton won them by 58 points in 2016, for example.

(In 2004, a good year for Republicans, Democrat John Kerry won conservative Black voters by 48 points.)

Ideology, however, has become far more aligned with voting patterns in recent years. Black voters seemed to follow this trend in 2020. Biden won Black conservatives by 20 points, a 38-point drop from Clinton’s. This came even as Biden picked up a little ground relative to Clinton among Black liberals and moderates. House Democratic candidates also carried Black conservatives by 20 points.

There’s just no recent historical analogy for what happened with conservative Black voters in 2020. It really broke the mold.

If Republicans chip away at Democrats’ support with Black conservatives, it still won’t change the fact that Black voters, overall, remain a very Democratic group.

Elections, however, aren’t won and lost by winning groups of voters. Margins are what matter.

If we continue to see movement among Black conservatives like we did in 2020, life would get easier for the GOP. Republicans aren’t going to need as wide victory margins among other groups to win elections.

The-CNN-Wire
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