The good news for President Trump in a new CNN-SRSS poll is simple: His approval rating is at 42 percent, higher than it has been in nearly a year. Trump generally argues that polls underestimate his support (a claim for which there’s no evidence), so he’ll no doubt be pleased with that result.

Buried in that poll, though, is a detail that won’t be reassuring to his party. His approval is at 42 percent overall. But among those who say they’re very enthusiastic about voting in November, he’s at only 38 percent support, with 60 percent saying they disapprove. Among those less enthusiastic about voting, as many people view Trump with approval as with disapproval.

Why does that matter? Well, in theory, because it means that the people most motivated to vote are also those least supportive of Trump. Which suggests that the people they’re going to vote for in November are not Republicans.

A recent Fox News poll shows that Democrats are indeed the group that’s more enthusiastic about voting.

But the picture is more complex than that.

First, Republicans generally have a turnout advantage — although, as FiveThirtyEight noted earlier this year, that effect tends to be muted when a Republican is in the White House. In a January Washington Post-ABC News poll, the Democratic enthusiasm edge manifested as Democrats being about as likely to vote as Republicans. That’s a big swing from past elections, but a different perspective than looking solely at enthusiasm numbers.

It’s also worth noting that a chunk of the group that says it’s very enthusiastic about voting in CNN’s poll is made up of Trump’s base of support. About 32 percent of those who are very enthusiastic about voting strongly approve of Trump — a higher percentage than those that strongly approve of him among those who are less enthusiastic about voting. Nearly 6 in 10 of those who are very enthusiastic about voting in the midterm elections strongly disapprove of the president.

As CNN notes, where those who are more enthusiastic about voting are most supportive of the president’s work is on the economy. Even there, though, only 45 percent of very enthusiastic respondents approved of how Trump was doing. Half disapproved.

The broader context for the CNN-SRSS numbers is that the Democrats’ position is worse now than it has been in six months, according to RealClearPolitics averages of polling on Trump’s approval and the generic congressional ballot (a standard poll question asking whom respondents plan to support in the upcoming House race, the Democrat or the Republican). In mid-December, Trump’s approval rating was 21 points underwater, with 37 percent approving and 58 percent disapproving in RCP’s average. Two weeks later, the Democrats saw their widest lead in the generic ballot — 13 points.

The two move in tandem and they’ve both drawn closer in the past month or so. As Trump’s approval improves, so does the Republicans’ position in November.

The Democrats still have a significant advantage in the midterm elections, thanks to the margins above and thanks to the number of retirements that have removed incumbents from a number of Republican-held House seats. Democrats being more enthusiastic about voting may very well manifest in a wave of Democratic victories in November. But the gulf Republicans faced in December is only half as wide now — meaning that their prospects are better than they were three months ago.