Washington CNN  — 

The Democratic advantage on the generic congressional ballot has tightened to 6 percentage points, a new CNN poll conducted by SSRS finds.

The poll finds that 50% of registered voters say they prefer a Democrat in their congressional district, while 44% say they want a Republican. That’s a major shift in favor of the GOP since February, when Democrats held a 16-point edge. It’s much closer to January, when their lead was just 5 points.

But Democratic voters are much more enthusiastic about casting ballots in November’s midterm elections.

About half – 51% – of Democrats and Democratic-leaning independents say they are extremely or very enthusiastic about voting for Congress in November, compared with just 36% among Republicans and Republican-leaning independents.

And at the same time, those voters who are deeply enthusiastic about voting give Democrats a better than 20-point lead on the generic ballot: 60% prefer the Democrat in their district, while 38% who prefer the Republican.

Overall, just 18% of voters approve of Congress, while 75% disapprove. And an even smaller share of those enthusiastic to vote in the fall, 11%, approve of the way Congress is handling its job.

Though Republicans control Congress, voters say they believe Democrats would do a better job of dealing with a host of key issues.

Among them: Health care (56% Democrats to 36% Republicans, a sharp change from 2010 when the two parties were nearly even on the issue following passage of the Affordable Care Act), the Russia investigation (51% Democrats to 35% Republicans), immigration (51% Democrats to 40% Republicans) and gun policy (48% Democrats to 40% Republicans).

The GOP is favored on just one issue: National security, at 48% to 40% Democrats.

The public is split over whether they prefer the Democrats or the Republicans in Congress on the economy (45% choose each party) and the federal budget (43% prefer the Democrats and 42% the Republicans).

The findings come just two weeks after Democrats won a stunning victory in a special congressional election west of Pittsburgh, where Conor Lamb – fueled in part by energized labor unions – narrowly defeated Republican Rick Saccone in a district President Donald Trump won by 20 percentage points in 2016.

The poll showed that Trump’s approval rating has ticked up to 42% – the highest since the 100-day mark of his presidency.

The CNN poll was conducted by SRSS on March 22-25 among a random national sample of 1,014 respondents, including 913 registered voters, reached on landlines or cell phones by a live interviewer. Results for the full sample have a margin of sampling error of plus or minus 3.7 percentage points. For registered voters, the margin of error is 3.8 points.

CNN’s Jennifer Agiesta contributed to this report.