Democratic campaign operatives have acknowledged that running against Donald Trump and the White House controversy du jour -- at the expense of more substantive policy issues -- could weaken their advantages heading into November’s midterms. And complicating their case further are signs of economic improvement, including recent labor statistics showing national unemployment at a near-20-year low of 3.9 percent.

Democrats point to polling and other data to argue that -- despite voters feeling better about the economy -- there is still anxiety about the future and that Democratic policies would provide more financial security in the long run. Party congressional campaigns are pushing, for example, the message that the GOP tax bill gave away more to corporations than to average Americans.

But efforts to explain the party’s plan to “revisit” the tax law if elected to the House majority underscore the difficult question Democrats are trying to answer: How do you talk about the economy when the economy is good?

“Every time [Democrats] deny the economy is starting to turn or get better for certain parts of the population, they also hurt themselves,” says party strategist Hank Sheinkopf. “They appear to be cheering on bad news.”

And Democrats could face a similar challenge on recent news about Trump’s plans to meet North Korean leader Kim Jung Un, seen as entirely separate issue but nevertheless one that relates to overall feelings of security. While success on that front is hypothetical at this point, opponents of the president are already trying to balance skepticism and applauding signs of progress. A CNN poll released this week, for example, found that 77 percent of Americans approve of the meeting.

That same survey found that 52 percent of voters approve of Trump's handling of the economy, up from 48 percent in March. And 57 percent of voters said things overall are going well, up from 49 percent registered in the last poll on that question in February. Notably, 84 percent cited the economy an either extremely or very important factor in how they will vote in November, up from 74 percent in February. And the survey found the Democrats' advantage on the generic ballot to be just three percentage points, down from six in March and 16 in February. (The RealClearPolitics average shows Democrats with a generic ballot lead of six points.)

The fundamentals still favor Democrats. Midterms are typically a referendum on the party in power, and Democrats this cycle have the added benefit of a president who remains unpopular beyond his base even as voters view the state of the economy positively. Several special and off-year elections have demonstrated Democratic enthusiasm and over-performance. The same CNN survey found that 53 percent of voters who identify as very enthusiastic say they are voting for the Democrat in their district, while 41 percent say they are backing the Republican. However, enthusiasm among Republicans has also ticked up to 44 percent, compared to 36 percent in March.

Parties out of power typically face a dilemma in campaigning against the party controlling the levers of government when the economy is improving. Republicans encountered the same dynamic in 2016, and tried to thread the needle between welcoming good economic news while also arguing it wasn't good enough. Trump apparently made that case, but he often threatens to imperil the GOP’s economic messaging with unrelated, and self-generated, controversies.

While Trump's behavior has certainly fueled energy among the opposition party, Democrats at the strategic and candidate level have stressed the importance of policy issues.

"I wouldn’t be talking about Trump almost at all," says Florida-based Democratic strategist Bob Doyle. "I'd run against Washington generically, arguing that politicians in Washington in both parties have let us down."

Doyle asserts that economic data doesn't tell the whole story, as it can overlook under-employment and lagging wages, which creates room for Democrats to score points. "When you’re a middle-class or working-class family, you not only talk about the economy in terms of your job, but you’re also talking about the cost of health care, or the cost of higher education. ... There's a lot of anxiety out there still."

Data compiled from Democratic pollsters Global Strategy Group for the Navigator Research project bears that out. The group's survey found that 67 percent of voters agreed with the liberal argument that "the economy may be growing but wealthy people at the top are getting so much more of the benefit than middle class and working people" while 33 percent agreed with the conservative argument that "things are generally going well economically – the national economy is booming, the stock market is hitting record highs, and businesses are creating new jobs all the time." The survey also found that 51 percent of voters say they worry about their financial future, while 25 percent say they worry about their current situation, like making ends meet.

"Just because people talk about the current moment being OK, there’s still a lot of uncertainty about the future," says GSG’s Nick Gourevitch. "The [economic] collapse isn’t too far in the rear view, and they don’t feel like they have retirement figured out or would be able to handle a big medical event."

Still, whether that longer-term concern compels voters to want to change course now remains an open question.

"The struggle is Democrats are not in power, we’re not in a position to be laying out this huge economic agenda" in the midterm the way they can in 2020, says Gourevitch.

In reacting to last week's jobs report, House Minority Leader Nancy Pelosi incorporated the sentiments reflected in the GSG polling into her messaging. "Corporations and the wealthiest 1 percent continue to hoard the benefits of the U.S. economy," she said in a statement. "Corporations are cheering their huge new tax breaks by enriching their executives and investors, while hard-working men and women see little help and rising health costs."

Republicans have tried to use those comments to their benefit. Last week they released a digital ad claiming Pelosi wants to raise taxes, referencing an interview in which she said Democrats would roll back the tax bill.

But the GOP also has its own messaging challenges on the economy. Last week, Florida Sen. Marco Rubio came under fire for saying, in an interview with the Economist, that "there's no evidence whatsoever” that money from the corporate tax cut has been “massively poured back into the American worker." (He later walked the statement back.) And Republicans are still working on selling the benefits of the new tax law to voters, and plan to spend millions on the effort.

Republican pollster David Winston has argued that while the tax changes will benefit GOP candidates, how each party addresses specifics related to the economy, particularly cost-of-living issues, will have a more significant impact on the outcome of November's elections.

In a Roll Call editorial this week, Winston cited polling from earlier this year that found half of voters named the cost of health care as either a first or second concern, while 29 percent named taxes.