The midterms swing voter: People who disapprove of Biden only a little

Everybody knows that a president’s job approval affects how his party does in congressional elections. But a close examination of midterm exit polls since 2006 shows this link is both stronger and more complicated than most analysts think.

Presidential job approval is often conceived in binary terms: Voters either like or don’t like how the current occupant is doing the job. Exit poll data from recent midterm elections, however, show that the degree of support or opposition matters a lot too.

Voters who weakly support or weakly oppose a president vote much differently in congressional elections than strong foes or fans do. Voters with strong views about a president are nearly certain - between 90 and 96%, depending on the year - to cast a ballot in House races in line with their view of the president.

The 2018 midterm elections were a perfect case in point. Forty-six percent of all voters strongly disapproved of President Donald Trump’s job performance, and 95% of them voted for Democrats that year. Likewise, 31% of voters strongly approved of him, and 94% of them voted Republican.

Those who feel less passionately, on the other hand, are less likely to let their feelings about the president determine how they vote for a member of Congress. Those who weakly approve of a president historically give, as a group, between 74 and 84% of their votes for congressional candidates of the president’s party. That’s a strong result, but it’s significantly below the near unanimity among strong supporters.

Along the same lines, those who weakly disapprove of a president are less unanimous in their opposition to a president’s party than strong presidential foes are. These voters are the most important in this year’s midterm elections.

The votes of weak disapprovers have ranged from a high of 38% support for George W. Bush’s GOP in the 2006 midterm to a low of 27% support for Barack Obama’s Democrats in 2010. Even so, the president’s party did not receive a plurality of these votes in midterm House elections going back to 2006.

The same trends are seen in Senate elections. Every Republican but one running in a competitive Senate race in 2018 received between 88 and 98% of the vote, according to exit polls, from those who strongly approved of Trump’s job. None got more than 4% of voters who strongly disapproved of Trump.

The one exception was Patrick Morrisey of West Virginia, who got only 80% support from Trump’s strong approvers, on top of a mere 46% of Trump’s weak approvers. Morrisey was running against Joe Manchin, whose unusual cross-party appeal made Morrisey the outlier.

Because there are so few Manchin-like senators, we can confidently model the 2022 House generic ballot based on President Joe Biden’s four-tiered job approval ratings. Biden currently garners a strong approval rating of only 18%, according to an average of three recent polls. He sports a horrendous 41% strong disapproval rating.

Given the expectation that virtually all voters in both “strong” camps will vote in line with their views of Biden, Democrats in the House and Senate would need to massively outperform historical trends with Biden’s weak approvers (currently 24% of voters) and weak opponents (13%) to have a prayer of running close to Republicans.

Remarkably, there is some evidence they are doing that. The Politico/Morning Consult poll releases data on the generic congressional ballot for each of the four tiers of presidential job approval. Its most recent poll shows congressional Democrats getting 95% support among Biden’s strong approvers, which is in line with past results. It also shows the party running at the high end of historic ranges among weak approvers (81% of whom say they will vote for a Democrat in November) and strong disapprovers (6% say the same).

Most important, the poll shows congressional Democrats actually leading among Biden’s weak disapprovers by a 7-point margin, 42% to 35%. This showing is the biggest reason why the poll shows Democrats ahead by 4 points.

Yet these data also show how hard it will be for Democrats to hold on to their current momentum in the midterm campaign. Unless Biden’s job approval ratings tick up appreciably, his party will need to win a plurality of the vote among weak Biden disapprovers to have a shot, both nationally for the House and in each closely contested Senate race.

The president’s party, however, has lost among this group by at least 20 points in every midterm House generic ballot exit poll since 2006. And in Senate exit polls, the president’s party normally loses by similarly large margins. Repeating anything close to that performance in November would doom Democrats across the board.

Democratic hopes of keeping their Senate majority rest on nearly every one of their candidates in swing states and districts having the bipartisan appeal of a Jon Tester or a Joe Manchin. That’s pretty unlikely.