As congressional Republicans fight to preserve their majorities, they may need to find a weapon more powerful than the big December tax cuts.

The new NBC News/Wall Street Journal poll shows that the tax-cut law, never broadly popular, has sagged in public esteem lately. Just 27 percent of Americans call it a good idea, down from 30 percent in January. A 36 percent plurality call it a bad idea, while the rest have no opinion.

Moreover, a majority gives thumbs-down on the plan when asked to consider its potential effects. Just 39 percent foresee a positive impact from a stronger economy, more jobs and more money in their pockets; 53 percent foresee a negative impact from higher deficits and disproportionate benefits for the wealthy and big corporations.

"Not a great starting point" for the fall campaign, said Fred Yang, a Democratic pollster who conducted the survey with Republican counterpart Bill McInturff. The telephone poll of 900 adults, conducted April 8-11, carries a margin of error of 3.27 percentage points.

Republicans began learning that lesson last month during a special House election in Pennsylvania. GOP strategists found the tax cuts an ineffective message against the Democratic candidates and dropped the issue as Election Day approached.

The Democratic victory in a district President Donald Trump had won by 20 percentage points in 2016 showed that tax cuts are "a political loser," says David Wasserman, a House analyst at the Cook Political Report.

The question now is how much effort GOP candidates sink into improving their stance on the tax-cut issue. They retain some advantages: Men still favor the tax cuts, although less strongly than women oppose it; so do rural residents, older men, and men without college degrees.

Yet working-class, middle-class and upper-class Americans all hold negative views of the tax-cut law. Women who have graduated from college call the tax cuts a bad idea by nearly a 3-to-1 margin.

Overall, the NBC/WSJ Poll shows Democrats with a seven-point edge over Republicans, 47 percent to 40 percent, on which party Americans want to win control of Congress this fall. Just 39 percent of Americans approve of Trump's job performance, while 57 percent disapprove.