President Trump at a rally in Springfield, Mo., on Friday. (Neeta Satam/Bloomberg News)

Midterm elections often serve as an indirect referendum on the president. It’s why the first midterms after the election of a new president are often rough for that president’s party: The honeymoon period has worn off, and voters realize that they hold the power to keep the president in check.

It’s unusual, though, that a president should be as central to a midterm election cycle as President Trump is to this one. New data from the Pew Research Center shows that the percentage of respondents who say their midterm vote has nothing to do with the president has hit a new low in the history of their polling.

The percentage planning to vote to express opposition to the president is, for the first time, equal to the percentage uninterested in sending a message. The only time since 1982 that a higher percentage wanted to express opposition to the president was in 2006 — a year that the Democrats romped.


(Philip Bump/The Washington Post)

That’s reflected in the enthusiasm measured among those who plan to vote for a Democratic or Republican congressional candidate. Two-thirds of those planning to vote for a Democrat say they’re more enthusiastic about voting than normal, the highest percentage on record.


(Philip Bump/The Washington Post)

But the percentage of Republicans saying that they, too, are more enthusiastic about voting than normal is also high — even higher than in the 2010 election, in which Republicans saw a historic wave.

Democrats and Republicans are energized in part because Trump has done a good job of keeping his base motivated. The percentage of members of the president’s party who say their vote is an endorsement of the president is higher than it was in 2014, when Republicans made gains against President Barack Obama’s party. It’s lower than Democratic support for Obama in 2010, though, a year in which interest in expressing support for the president didn’t do much to protect his party.


(Philip Bump/The Washington Post)

Part of the problem in 2010 was that, while Democrats may have wanted to demonstrate support for Obama, his base didn’t turn out as heavily as Democrats would have hoped. The question in 2018 is whether Trump supporters will demonstrate their support by actually voting. That brings us back to the second graph above: In 2010, only 42 percent of those supporting Democratic candidates said they were more enthusiastic about voting than normal. This year, 59 percent of Republicans say the same thing.

More interesting, perhaps, is Pew’s analysis of what issues are most important to voters this year.

The most important issue overall? The Supreme Court. Since 2016, the percentage of those supporting Republicans who’ve cited the Supreme Court as the most important issue has increased slightly. The percentage of Democrats pointing to the court has spiked by 19 points.


(Philip Bump/The Washington Post)

Republican interest in various issues has waned since 2014 and 2016. On health care — consistently shown to be a central issue to this election — the gap in interest between Democrats and Republicans has grown from five or six points in 2014 and 2016 to an 18-point difference in importance between the parties this year.

On other issues that Trump cites regularly — the economy, immigration, terrorism, trade — interest is lower than on health care and the Supreme Court and has remained flat or dropped among Republicans.

What’s more, voters believe that Democrats will do a better job of handling a number of key issues, including the economy.


(Philip Bump/The Washington Post)

The election has often been understood as a turnout contest: Can Democrats overcome the traditional advantage Republicans have in low-interest midterm elections? This data, though, suggests that Democrats also have a distinct advantage on the issues.

As for that point we led with, that voters want to have a check on the new president? In the Trump era, that comes in very concrete terms. Pew found that voters were more likely to say that they worried Republicans wouldn’t focus enough on oversight of the Trump administration (64 percent) than worry that a Democratic-led Congress will focus too much on investigating the president (55 percent).

A good reason for Trump to want to keep his base energized.