After months of shying away from the toxic topic, Democrats increasingly are embracing political rhetoric that flirts with the impeachment of President Trump – signaling a strategy that could work its way into the mainstream in the 2018 midterms.

From the base, the party sees encouragement. A petition with 4 million signatures demanding Trump’s impeachment and a survey showing 70 percent of Democrats backing at least hearings on the matter could nudge Democrats further into the impeachment camp in the new year.

The publication of the “Fire and Fury” tell-all, meanwhile, has only emboldened Trump’s critics, by seeming to raise questions about his stability – which the president openly confronted in a weekend tweet-storm declaring he is a “very stable genius.”

Democrats must win 24 House seats and two Senate seats to regain control of Congress in 2018, but have a historically tough time motivating their voters in non-presidential years.

'Smart Democrats know it’s a dumb idea.' — legal commentator Andrew McCarthy, on impeachment push

Neil Sroka, spokesman for Democracy for America, a liberal activist group that endorses and raises money for Democratic candidates, claimed the impeachment push has public support.

“Democrats should run on an inclusive, populist agenda of free college and paid family leave, but shouldn’t shy away from supporting impeachment,” Sroka told Fox News.

HOUSE REJECTS TRUMP IMPEACHMENT RESOLUTION

“Millions of people around the country support impeaching the president. Democratic candidates in deep blue districts can and should be for impeachment,” Sroka continued. “It would be politically stupid for any Democrat to come out against impeachment.”

Last month, 58 House Democrats voted to bring an impeachment resolution up for debate. While party leadership has publicly shunned the idea, Democrats recently tapped Rep. Jerrold Nadler of New York to be ranking member of the House Judiciary Committee, replacing disgraced ex-Rep. John Conyers. Washington Post columnist Paul Kane described the choice as a move “to ready themselves for a battle with President Trump that could end with impeachment proceedings,” given Nadler’s expertise in constitutional law.

Some impeachment advocates say it doesn’t matter that Special Counsel Robert Mueller’s investigation into possible collusion between the Trump campaign and Russia isn’t complete.

In November, Rep. Steve Cohen, D-Tenn., and four other Democrats introduced five articles of impeachment against Trump. Reps. Brad Sherman, D-Calif., and Al Green, D-Texas, were the first to introduce an impeachment resolution in July, alleging obstruction of justice in the Russia investigation. Rep. Maxine Waters, D-Calif., ended one speech last year with an "impeach 45" chant.

Even Sherman, though, expressed caution against making impeachment a campaign issue.

“This is a matter of constitutional principal, not politics,” Sherman told Fox News. “Members should look at the actions of the president and determine whether they believe he obstructed justice or committed other acts warranting impeachment. … Talk of impeachment has already had an effect. Imagine how President Trump would behave if he thought there was absolutely no risk of impeachment. We need not wait until all the various investigations give us a complete catalog of all of Trump’s wrongdoings.”

The publication last week of Michael Wolff’s “Fire and Fury: Inside the Trump White House” fueled the impeachment fever.

Liberal billionaire Tom Steyer, who has spent $20 million to promote impeachment, sent a copy of the Wolff book to all 535 members of Congress. Steyer’s NeedToImpeach.com petition collected 4.1 million signatures. He told a California radio station KQED Friday: “It is an open-and-shut case, that he has met the criteria for impeachment. We're supportive of the Mueller investigation, he is investigating two out of the nine criteria that this president has met.”

Steyer has said in TV ads that past presidents have been impeached for lesser crimes.

But where Trump critics see an “open-and-shut” case, others see a major pitfall for the party.

“Steyer’s assumption is that Trump committed espionage with Putin. If proven, he would be quite right, but it hasn’t been proven,” conservative legal commentator and author Andrew McCarthy told Fox News. “The country will not broadly find it attractive if there is a lack of evidence. Fair-minded people will not want to impeach. Smart Democrats know it’s a dumb idea.”

McCarthy nevertheless believes Democrats will feel pressure from a rabid base to run on impeachment, and some members could fear a primary if they aren’t on board.

“The base can make Democrats do politically stupid things,” said McCarthy, former chief assistant U.S. attorney in New York. “If the Democrats’ front and center issue is impeachment, they will not win in the midterms. It would be a bad strategy to run on.”

A Wall Street Journal-NBC poll last month found 41 percent of Americans want Congress to hold impeachment hearings. Of that, 70 percent of Democrats, 40 percent of independents and 7 percent of Republicans back a House inquiry.

Only Presidents Andrew Johnson and Bill Clinton were impeached in the House, where it takes just a majority, and both were acquitted in the Senate, where it takes a two-thirds supermajority to remove. Clinton’s 1998 impeachment was for perjury and obstruction of justice in connection with the Monica Lewinsky scandal, while Johnson’s 1868 impeachment was about violating the Tenure of Office Act after he fired War Secretary Edwin Stanton. President Richard Nixon resigned after the House Judiciary Committee approved articles of impeachment over Watergate, to avoid impeachment and removal. Article II of the Constitution says impeachment can be based on "treason, bribery and other high crimes and misdemeanors."

“Many Democrats will want to impeach Trump even if they don’t have anywhere near the numbers in the Senate,” McCarthy said. “That’s in part because they hate Trump and in part because they’re still sore about the Clinton impeachment 20 years ago.”

But Sroka is taking a just-you-wait approach on the Senate numbers.

“We’ll see what two-thirds looks like,” Sroka said. “Given the range of impeachment-worthy offenses by Donald Trump, it’s difficult to compare with what Republicans tried to impeach Bill Clinton over, or what Andrew Johnson was impeached for.”