Polling numbers that have buoyed Republican spirits in recent weeks have crept back down in a new survey, which pegged the Democratic advantage at 10 percentage points.

Key measures showing which party voters prefer to be in charge on Capitol Hill, along with voter enthusiasm, had evened out as Americans' perceptions of the economy brightened and President Trump's diplomatic efforts with North Korea added to their views that he was handling parts of his job well, even though they remained dissatisfied with his performance overall.

That momentum has reversed in fresh polls this week.

Not only did the new NBC News/Wall Street Journal poll show a 10-point lead for the Democrats over the Republicans on the generic ballot, but a 16-point advantage in voter enthusiasm. Sixty-three percent of Democrats expressed a high level of interest in the midterm elections; only 47 percent of Republicans said the same. Additionally, 48 percent of respondents said they were more likely to vote for the congressional candidate who promised to put a check on Trump; only 23 percent said they were less likely to vote for such a candidate.

This survey followed one from Quinnipiac University that showed Democrats had a 7-point lead on the generic ballot, just where the party needs to be to have a legitimate shot of flipping the 24 seats it needs to capture the House in November. A third poll from this week, from Reuters/Ipsos, showed the Democrats ahead on this indicator by 11 points.

Trump's own job approval rating in the NBC News/Wall Street Journal Poll was on the high end of his average range since he was inaugurated in January of last year, coming in at 44 percent. The lower the president's approval rating on Election Day in November, the stiffer the political headwinds for congressional Republicans.

Yet this survey suggests that an improving Trump might not be enough to save the GOP. This dynamic wouldn't be unheard of, however.

During President Barack Obama's tenure, voters generally gave him high personal marks, but rejected his party in two midterm elections because of displeasure with policies that sparked high enthusiasm to vote among Republicans.

With Trump, voter angst is reversed. There tends to be a decent amount of support for this president's policies, but deep disapproval with how he conducts himself personally. That disapproval could contribute to big GOP losses in the fall even if voters give the economy a thumbs up.