If “it’s the economy, stupid,” as James Carville argued a generation ago, then Democrats may be heading into a midterm trap. A new CBS/YouGov poll shows Americans getting more enthusiastic about economic growth, and crediting Donald Trump more with the expansion:

Nearly 2 in 3 Americans think the nation’s economy is in good shape, and most of them believe President’s Trump’s policies are at least somewhat responsible for that. More Republicans rate the economy positively than do Democrats.

As Congressional primaries continue and Americans look ahead six months to their midterm votes, Mr. Trump looks like a positive factor among Republicans, 7 in 10 of whom say they’d prefer a candidate he backs — but the president’s influence is limited to his own party. More Independents say they’re less likely to support a candidate backed by Mr. Trump.

There’s still plenty of nuance in these numbers, but they’re moving in the right direction for both Trump and the GOP. Four months ago in the same polling series, only 46% of respondents thought Trump had made the economy better, with 54% disputing that contention. This poll didn’t ask the question in the same way, but Trump’s support has ticked up, especially in “strong Trump supporter,” going from 18% to 23% in the intervening period.

Much of this appears to be a shoring up on the Right, though. In January, 48% of Republicans called themselves “strong Trump supporters,” but that number is 57% in the latest survey. It’s ticked up slightly among independents too, going from 14% to 16%. Other indicators look less promising for broadening Trump’s appeal:

People who are more conditional supporters are slightly more likely to say he’s looking out a lot for business – including his own – more so than people like them. One of the biggest indicators of being a strong [T]rump supporter is that those backers feel he is looking out for people like them above big business, the wealthy, and his own business interests.  And they give him much more credit for the economy than do others, including more conditional backers.

Most Republicans think Mr. Trump is keeping his campaign promises: 50 percent say he is keeping most of them, and another third say he’s keeping some and hasn’t gotten around to the others yet. The president’s strongest backers are especially likely to say he’s keeping most of the promises he made during the campaign.

Of all the results in this poll, however, this one has to be the most encouraging of all to the GOP:

That’s not quite the form used in generic congressional ballot polls, but it’s close enough and adds up to a D+2. That’s a sharp difference from previous YouGov generic balloting, mainly with the Economist, which has had D+5 and D+9 in its most recent two iterations.  Trump ties with Bernie Sanders for best endorser, with 29% of voters saying they’d be more likely to vote for a congressional candidate with their backing. Mike Pence scores 28%, but Nancy Pelosi comes in dead last at 13%, with only 30% of Democrats likely to follow her lead. Independents are three times as likely to follow Trump’s lead than Pelosi’s (27%/8%), and only slightly more likely to follow Bernie Sanders’ endorsement (28%).

We’re still a long way out from the midterms, but the trends don’t look good for Democrats, and their leadership looks like voting-booth poison. They’d better hope Carville got it wrong.