Progressive Democrats of America holds a news conference to announce the launch of a Medicare for All Caucus at the Capitol on Thursday, July 19, 2018.

Those contrasting views explain why President Trump and fellow Republicans seek to slap that label on Democrats across the board. They also explain why most Democratic presidential candidates, apart from the self-styled Democratic socialist Bernie Sanders, reject the label and call themselves capitalists.

As a philosophical label, socialism fares dismally alongside capitalism in public sentiment. Just 18 percent of Americans react positively to the mention of socialism, while 50 percent react negatively. Capitalism draws almost exactly the inverse reaction: 50 percent positive and 19 percent negative.

That paradoxical verdict emerges from the new NBC News/Wall Street Journal poll. And it underscores the challenges facing both President Donald Trump and his Democratic adversaries.

Twenty months before Election Day, Americans have a clear message for 2020 presidential candidates: keep your socialist hands off our government programs.

As a practical matter, however, average Americans who have long suffered from slow-growing wages want more help from their representatives in Washington. So the poll shows that a 55-percent majority says government should do more to solve problems and meet their needs, compared to 41 percent who say government is doing too many things already. Americans have expressed a desire for more government help by double-digit margins throughout Trump's presidency.

Thus Democratic candidates have gravitated toward proposals to expand health care coverage through "Medicare for All," lower the costs of college and prescription drugs, and replace tax cuts for the affluent with cuts for working and middle class voters. They have also embraced government action to curb climate change.

Those divergent views outline the test facing each side in the 2020 campaign. Republicans need to champion capitalism without conveying unwillingness to help average families; Democrats need to tout the assistance they'd provide without affirming the charge that they seek a fundamental transformation toward a socialist system.

The poll shows that Americans across the partisan divide express positive views of capitalism — Republicans by overwhelming margins, independents and Democrats by narrower ones. Democrats marginally express positive views of socialism, independents and Republicans strongly negative views.

On the role of government, Republicans say government is already doing too much by more that a two-to-one margin. Democrats by four-to-one say government should do more; independents side with the Democratic view by a comparatively slim 54 percent to 44 percent margin.

Support for additional government help follows the demographic contours of each party's core supporters. Woman, non-whites, and residents of urban areas want more by lopsided margins. Opinion among men, whites, suburbanites and rural residents divides more evenly.

The strongest opposition to more government help, by a 56 percent to 41 percent margin, comes from white men without college degrees — the staunchest supporters of the Trump-era GOP. College-educated white women reverse those numbers, with 54 percent supporting more government help and 41 percent opposing it.