As Democrats begin an impeachment inquiry, President Trump spent Sunday vigorously defending himself on Twitter and sharing cable news clips of his most ardent devotees insisting that he did nothing wrong in asking the Ukrainian president to investigate his political rival, former vice president Joe Biden.

Trump highlighted one quote from a longtime evangelical pastor warning of particularly dire consequences if the Democrats follow through.

“If the Democrats are successful in removing the President from office (which they will never be), it will cause a Civil War like fracture in this Nation from which our Country will never heal,” Trump tweeted, adding his own parenthetical to a quote from Robert Jeffress, a Southern Baptist preacher speaking on “Fox & Friends Weekend” on Sunday.

Trump’s tweet invoking civil war marks a notable escalation in his rhetoric about the impeachment inquiry and also highlights his close relationship with Jeffress, a pastor known for viciously attacking other faiths who holds sway over both evangelical voters and the president.

The tweet drew an immediate reaction, becoming the lead story on the Drudge Report and prompting critics — including one sitting Republican congressman — to accuse Trump of stoking violence and diminishing the reality of true civil war.

“I have visited nations ravaged by civil war. @realDonaldTrump I have never imagined such a quote to be repeated by a President,” tweeted Rep. Adam Kinzinger (R-Ill.), a decorated Air Force veteran who served as a pilot in Iraq and Afghanistan. “This is beyond repugnant.”

House Democrat Don Beyer of Virginia urged other Republicans to join Kinzinger in denouncing Trump’s rhetoric, tweeting, “The president is testing to see who will echo or silently accept threats of violence.”

Presidential hopeful Beto O’Rourke, too, called upon GOP members to speak out. Trump’s words can have violent consequences, the former Democratic representative tweeted, citing the mass shooting in El Paso and asking for Republicans to decry him “before more are harmed in his name.”

Two Senate Democrats, Chris Murphy (Conn.) and Brian Schatz (Hawaii), also condemned the president’s tweet in a back-and-forth in which Murphy described the message as “so frightening.”

“He is going to keep talking like this,” Murphy tweeted, “and some people are going to listen and do what he asks.”

The idea of a U.S. civil war did not come from Trump directly. Instead, he quoted a high-profile and contentious Texas pastor who has stood with the president since the earliest days of the 2016 campaign.

Jeffress, who fronts a megachurch in Dallas that attracts 14,000 worshipers and hosts his own religious television and radio shows, introduced then-candidate Trump at a campaign rally in January 2016. A month later, he gave an impassioned speech in Fort Worth, endorsing Trump, who he said would be a “true friend” to evangelical Christians, at a time when many religious conservatives still wavered on whether to support the former Democrat with a scandalous past.

Since then, the pastor has been one of Trump’s most outspoken supporters. He uses the Bible to defend the president’s actions and brushes away allegations of immoral conduct, from extramarital affairs to alleged sexual assault, by emphasizing Trump’s record on filling the judiciary with conservative justices and pushing for policies that limit access to abortion.

His speeches regularly appear on Fox News, and Jeffress gave a private sermon to the president-elect and his family before Trump was sworn in on Jan. 20, 2017. He was one of the guests honored by name at a dinner Trump held for evangelical leaders. Trump has shared and replied to Jeffress in the past on Twitter, promoting the pastor’s book releases in 2017 and last January. The pair have appeared together in public on several occasions.

Jeffress has called “Never Trump” Christians “absolutely spineless morons” and compared them to the German Christians in the 1930s who did not try to stop the Nazis. He has called the Mormon Church a “cult,” and personally attacked Republican Mitt Romney over his faith in 2011. He once compared Trump’s border wall to the gates to heaven, because both signify “not everybody’s going to be allowed in.”

Since Democrats began moving toward impeachment last week, Jeffress has repeatedly sounded grim warnings. On Friday, he told Fox Business Network host Lou Dobbs, “I really don’t like what’s going to happen to this nation” if impeachment succeeds, adding, “If he is removed, this country is finished.”

The Jeffress quote that Trump tweeted Sunday evening is the first time the president has referenced civil war on Twitter. But as The Washington Post’s Greg Jaffe and Jenna Johnson have reported, cable news pundits on both sides of the spectrum have already begun using the term with regularity to describe the nation’s political conflict.

In one notable case in February, former U.S. attorney Joseph diGenova on Fox News and Trump critic and political analyst Nicolle Wallace on MSNBC both declared that the U.S. was “in a civil war,” though both pundits later walked back their rhetoric to claim they meant a war of words and ideas. Although it is “not entirely out of the question,” Stanford University political scientist James Fearon told The Post in March that he dismissed the idea of the United States being on the verge of a war with itself as “basically absurd.”

It’s not clear from Trump’s tweet or Jeffress’s interview whether he was referencing actual violence as the outcome of an impeachment, but many critics said that the president’s use of the term was troubling. The White House did not immediately respond to a request for comment clarifying the president’s intentions.

The Oath Keepers, a far-right militia group composed of former military and law enforcement officers, apparently took the message literally, saying in a Twitter thread that the United States is “on the verge of a HOT civil war. Like in 1859.”

The group claims to protect the Constitution “against all enemies,” which, they say, includes Democrats who are trying to impede Trump’s “rightful power." The organization is described by the Southern Poverty Law Center as “one of the largest radical anti-government groups in the U.S. today."

“Lincoln created the Republican Party and gave his life in order to save the Union. Trump ruined the Republican Party and now threatens to destroy the Union in order to save his job,” tweeted Rep. Jamie B. Raskin (D-Md.).

Schatz echoed that concern.

“This is just a reprehensible way to talk and people could get hurt,” Schatz tweeted. “It’s clear now [Trump] will allow the Republican Party to eat itself and will tear the country apart if he thinks it gives him an advantage of any kind.”