One of the Democratic Party’s most prominent financial backers is demanding that lawmakers and candidates on the left support removing President Trump from office, putting pressure on Democrats to make Mr. Trump’s ouster a defining issue in the 2018 midterm elections.
Tom Steyer, a billionaire California investor who spent more than $91 million supporting Democrats in the 2016 elections, issued the demand to his party in a letter on Wednesday. In his message, Mr. Steyer described Mr. Trump as a “clear and present danger to the republic” and called on Democrats to pledge that they would seek to remove him from office if they take control of Congress next year.
Mr. Steyer — who is considering a run for Senate, perhaps against Senator Dianne Feinstein, a fellow Democrat — cited a range of acts by Mr. Trump to justify impeachment, including the president’s “relationship with Vladimir Putin and Russia,” allegations that Mr. Trump has used the presidency to “promote his own business interests” and his “seeming determination to go to war.”
And he pointed to mounting expressions of concern on the right, including the warning by Senator Bob Corker, Republican of Tennessee, that Mr. Trump was at risk of fomenting a world war, and reports that Secretary of State Rex W. Tillerson described Mr. Trump as a “moron.” Democrats, Mr. Steyer said, should be no less confrontational.
“This is not just an issue of Twitter screeds but what it means for a person who has control over our nuclear arsenal,” Mr. Steyer said, adding in a plea to lawmakers: “I hope you will make your position clear so that Democratic voters who are under constant attack by this administration, know their elected representatives have the patriotism and political courage to stand up and take action.”
The letter, which was sent to Democratic congressional offices and the party’s House and Senate campaign committees, and shared with The New York Times by an aide to Mr. Steyer, represents a significant boost to efforts on the left to make impeachment a mainstream political consideration.
With Republicans in full control of Congress, there is no prospect in the near term that the president might be impeached. Even if Democrats pull off the unlikely feat of winning the House and Senate next year, it is unclear party leaders would be inclined to try to drive Mr. Trump from the White House.
Congress can only remove the president with a vote by two-thirds of the Senate. The Constitution specifies that a president can be impeached for “treason, bribery or other high crimes and misdemeanors,” though in practice there are widely divergent views on what represents an impeachable offense.
A handful of Democrats in Washington have backed proposals to eject Mr. Trump, including an impeachment resolution unveiled by Representative Al Green of Texas, and opinion polls have found considerable support for impeachment among Democratic voters.
But Democratic leaders have mainly focused on attacking Mr. Trump’s policy agenda; they have urged rank-and-file liberal activists to hold off on talk of impeachment while the gravest investigations into Mr. Trump’s conduct run their course.
Some party strategists are also concerned that putting impeachment on the ballot in 2018 could backfire, because so many Democratic senators are seeking re-election in states Mr. Trump won.
But Mr. Steyer, 60, may not be an easy figure for Democrats to ignore: He was the single biggest liberal donor in the last two federal elections, making climate change his signature issue and insisting that Democrats support action to curb carbon emissions. Mr. Steyer repeatedly denounced Mr. Trump’s environmental record in his letter.
More recently, Mr. Steyer has been weighing a 2018 campaign in California. His letter may be a signal that he is serious about taking on Ms. Feinstein, a long-tenured moderate, in a primary election next year. Ms. Feinstein, 84, announced this week that she will seek another term, stirring talk of a challenge on the left.
Though Mr. Steyer did not mention Ms. Feinstein by name, his letter appeared to allude several times to deferential comments Ms. Feinstein made about Mr. Trump in August, when she counseled “patience” to restive Democrats and suggested Mr. Trump could change to become “a good president.”
“It is clear for all to see that there is zero reason to believe ‘he can be a good president,’” Mr. Steyer wrote in his letter.
A national opinion poll published in August, by the Public Religion Research Institute, found that impeaching Mr. Trump was a minority position, but a popular one among Democratic voters. About 7 in 10 Democrats said Mr. Trump deserved impeachment, while 40 percent of Americans in general took the same view.
That quite likely makes impeachment a popular idea in Mr. Steyer’s home state, which is the largest blue state in the country and a stronghold of liberal opposition to Mr. Trump.