Republican voters may be getting complacent, and it could cost them the U.S. House of Representatives, according to a new internal poll conducted by the Republican National Committee.

The poll presents dim news for Republicans, Joshua Green of Bloomberg Business reported on Tuesday.

The study, based on polling conducted by Public Opinion Strategies, showed that 71 percent of respondents said they think it's "extremely" or "somewhat likely" that Democrats will regain control of Congress, versus only 25 percent who said the opposite.

"The Democrat(ic) party holds an image advantage over the GOP.”

Democrats hold a 9-point edge over Republicans on a generic ballot, the poll says, along with "a wide gender gap and generation gap." Democrats are "favored by women of all ages and also by men aged 18-44," Green writes.

Republicans and Trump supporters see it differently.

"Fully half of self-identified Republicans don’t believe Democrats are likely to win back the House," Green writes. "And within that group, 57 percent of people who describe themselves as strong Trump supporters don’t believe Democrats have a chance (37 percent believe they do)."

The problem for Republicans, however, is perceived voter complacency.

Despite President Donald Trump's boasting about a "red wave" in November that the president claims "could increase Republican majorities," Trump's tactics "appear to have lulled GOP voters into complacency, raising the question of whether they’ll turn up at the polls," according to Green's analysis of the poll.

The report urges rank-and-file Republicans to make sure their voters actually show up.

"We need to make real the threat that Democrats have a good shot of winning control of Congress," the report says.

The issue for Republican voters, the study finds, is that their trust in Trump may give them the impression there's nothing at stake in the midterm elections, thus causing them to abstain from voting.

Trump has been touting a "red wave" (something he has made up without any evidence to support it) that will continue the Republican majorities in Congress. Since June, the president has tweeted about it seven times, though it's usually something he says "might" happen.

This, the survey says, may actually be imperiling Republicans because their voters might just sit out the midterm elections, believing their vote won't matter.

Skepticism about polls plays a factor, too.

"While a significant part of that lack of intensity is undoubtedly due to these voters’ sentiments toward the President, it may also be partly because they don’t believe there is anything at stake in this election," the study authors write. "Put simply, they don’t believe that Democrats will win the House. (Why should they believe the same prognosticators who told them that Hillary was going to be elected President?)"

Despite showing that 40 percent of respondents think the country is heading in the right direction, the POS poll, which should be good news for the incumbent party in power, Republicans are facing another problem - simply having enough voters.

It's true that Trump enjoys substantial approval within his own party.

"Republicans don’t have a ‘base problem,’" the report says. "Those voters who strongly approve of the President and those who support both his policies and leadership style are genuinely passionate about voting in the election and are voting GOP lock, stock, and barrel."

Trump has tried to use his base's trust to drum up fears that he could be impeached if Democrats win enough seats.

"If it does happen, it’s your fault, because you didn’t go out to vote. Okay? You didn’t go out to vote," Trump said at a Montana rally earlier this month. "You didn’t go out to vote. That’s the only way it could happen."

Unfortunately for the GOP, Trump's base only accounts for about 25 percent of the electorate, which the survey says is "dwarfed by the 44% of voters who strongly disapprove of the President and are just as committed to DEM candidates and voting in November."

Further complicating matters, the study writes, are "soft" supporters. Those are voters "who ‘somewhat approve’ of Trump and those who support the President’s policies but not his leadership style are the ones posing a challenge to the party."

"Soft" Republicans are also aligning more with Democrats on spending issues, Bloomberg notes.

"The survey found that increasing funding for veterans’ mental health services, strengthening and preserving Medicare and Social Security, and reforming the student loan system all scored higher than Trump’s favored subjects of tax cuts, border security, and preserving the Immigration and Customs Enforcement agency."

The study says that "special attention should be paid to the messaging regarding Social Security and Medicare." It also points out that "the challenge for GOP candidates is that most voters believe that the GOP wants to cut back on these programs in order to provide tax breaks for corporations and the wealthy."

"The determining factor in this election," the study concludes, "is how voters feel about President Trump."