WASHINGTON — President Trump intervened Monday in the West Virginia Republican Senate primary, pleading with voters a day before the election to oppose the former mine operator Don Blankenship, and signaling Republican anxiety over the prospect of forfeiting yet another red-state Senate race.
Mr. Trump’s decision to speak out came after Senator Mitch McConnell of Kentucky, whom Mr. Blankenship has targeted with deeply personal attacks against his wife’s ethnicity, urged the president to weigh in against Mr. Blankenship’s candidacy, according to Republican officials familiar with the conversation.
Mr. Trump quickly agreed, suggesting in a tweet that a victory by Mr. Blankenship would lead to a reprise of the embarrassing loss Roy S. Moore suffered last year in Alabama, a reliably Republican stronghold.
“Don Blankenship, currently running for Senate, can’t win the General Election in your State…No way!” Mr. Trump wrote on Monday morning, before referring to other Republican candidates in the primary. “Remember Alabama. Vote Rep. Jenkins or A.G. Morrisey!”
The maneuvering by party leaders comes before a handful of states — including Indiana, Ohio and West Virginia — hold primary contests on Tuesday. Increasingly nervous Republican leaders want to nominate candidates who can help the party keep control of Congress in this fall’s midterm elections.
Mr. Trump warned that if Mr. Blankenship prevails in the primary it would all but ensure the re-election of the incumbent, Joe Manchin III, whom Republicans view as one of the most vulnerable Senate Democrats. Mr. Blankenship, the former chief executive of Massey Energy, served a year in federal prison after being convicted of conspiring to violate mine safety rules in connection with the Upper Big Branch mining disaster in 2010 that claimed 29 lives.
[Read more about Don Blankenship’s campaign here.]
The tweet on Monday was a political gift to Representative Evan Jenkins and Attorney General Patrick Morrisey, Mr. Blankenship’s two Republican rivals, in a state Mr. Trump won overwhelmingly in 2016 and where he remains popular.
Both men swiftly seized on Mr. Trump’s comments, weaving them into their final stump speeches, crafting last-minute digital ads and recording new automated phone calls.
”President Trump just announced this morning his support for Evan Jenkins,” a Jenkins robocall declared, taking some liberties with the president’s tweet, which did not favor him over Mr. Morrisey. The recording began with the phrase “This is a Trump voter alert” as it sought to further align Mr. Jenkins with the president.
In a statement responding to Mr. Trump, Mr. Blankenship said the president “is a very busy man and he doesn’t know me and he doesn’t know how flawed my two main opponents are in this primary.” He added that the “establishment is misinforming him because they do not want me to be in the U.S. Senate and promote the president’s agenda.”
That Mr. Trump would step into the contest at all underscores how alarmed party officials are about the prospects of a Blankenship victory.
The president has felt burned by Republicans when he injected himself into other races only to see his preferred candidates fall short. A victory by Mr. Blankenship would be highly embarrassing to Mr. Trump, coming on the heels of his inability to lift party nominees in Pennsylvania this year and in Alabama in December.
But the race may be close enough that Mr. Trump’s last-minute intervention proves enough to derail Mr. Blankenship, a power play that would only underscore his clout with the party base.
White House aides and Senate Republicans have been discussing for the last week whether the president should comment on the primary, and agreed he should do so if it became clear Mr. Blankenship could win, three officials familiar with the deliberations said.
By Friday, when party officials received internal polling showing that Mr. Blankenship was still in the hunt, they ratcheted up pressure on Mr. Trump to speak out against the former coal executive, who was imprisoned until last year and remains on probation.
White House officials had already begun considering potential language for a tweet over the weekend. In a wide-ranging call with Mr. McConnell on Sunday that was initiated by Mr. Trump, the president indicated he was willing to weigh in on the race. The president’s aides said he may record an automated call of his own against Mr. Blankenship.
Still, Mr. Trump has been intensely focused in the last week on the special counsel’s investigation into Russia and the uneven defense of a payment to a pornographic film actress offered by his new lawyer, Rudolph W. Giuliani, a former mayor of New York. As a result, administration officials were not fully certain what Mr. Trump would do about the West Virginia race until the early morning tweet.
Though Mr. Trump willingly intervened in the primary contest, some West Wing aides believe that the fight is more about Mr. McConnell, the majority leader, than the president. And they grumbled in the hours after the tweet that some Republican lawmakers, in particular Mr. McConnell, are inconsistent when it comes to what Mr. Trump’s policy should be on engaging in primaries.
Mr. Blankenship has faced a series of attacks from Republican groups aligned with Mr. McConnell for his role in the Upper Big Branch mining tragedy. He has also been criticized for keeping his official residence in Las Vegas and refusing to fully disclose his extensive financial holdings.
The attacks sent Mr. Blankenship’s poll numbers tumbling, but with Mr. Jenkins and Mr. Morrisey dividing votes, he has remained in contention. Internal surveys taken by his rivals indicate that Mr. Blankenship is near the top of the field.
That is partly because he has framed his conviction as a persecution by President Barack Obama’s Justice Department, a strategy aimed at tapping into the deep animus toward a former president who many in the state believe waged a “war on coal.”
In recent weeks Mr. Blankenship dipped into his personal wealth to air a series of incendiary ads targeting the family of Mr. McConnell, who is married to Transportation Secretary Elaine Chao.
“Swamp captain Mitch McConnell has created millions of jobs for China people,” Mr. Blankenship said in one commercial, alluding to the shipping business of Mr. McConnell’s father-in-law. Mr. Blankenship has also referred to Mr. McConnell’s father-in-law, an American citizen, as “a wealthy Chinaperson.”
Mr. Blankenship also called Mr. McConnell “Cocaine Mitch” for far-fetched claims that a ship connected to Ms. Chao’s father once smuggled drugs.
Mr. McConnell, who is deeply unpopular among Republican primary voters, has largely avoided wading into the feud, but has been privately fuming about the attacks on his wife’s family.
He has, though, been able to find some amusement in his new nickname, jokingly answering the phone “Cocaine Mitch,” according to one of his advisers.
Last week, he emailed an ally in evident wonder: “I never even smoked cigarettes.”
Until Monday, the closest the president had come to weighing in on the race was when he brought Mr. Jenkins and Mr. Morrisey to a tax-themed event he held in West Virginia and sat between them. (He even polled the audience to gauge who had more support.)
Part of the challenge for the Republican establishment has been that Mr. Jenkins and Mr. Morrisey have largely targeted each other, most recently during a bitter Fox News debate last week. Neither has been able to emerge as the clear front-runner, and Republican leaders do not have a strong preference between the two.
Mr. Jenkins is a former Democrat who represents the coal-producing part of the state, having upset a veteran incumbent in 2014, while Mr. Morrisey is a New Jersey transplant who made a name for himself suing the Obama administration.
They each hoped Mr. Trump’s late intervention could help them persuade undecided voters less than 24 hours before polls open.
In an interview, Mr. Morrisey, who until this weekend had largely ignored Mr. Blankenship, said the president’s statement “sends a message that West Virginia voters should reject the criminal convict Don Blankenship.”
Reflecting how tight the race has become in its final hours, Mr. Morrisey aimed withering criticism at Mr. Blankenship.
“This is someone whose whole career demonstrates he believes he is above the law,” he said, asserting that Mr. Blankenship would be “crushed” in the general election against Mr. Manchin.
Mr. Blankenship, though, said “no one, and I mean no one, will tell us how to vote,” and seemed to suggest that Mr. Trump had drifted from the spirt of his own candidacy by not embracing the hard-edged campaign he had waged.
”As some have said, I am Trumpier than Trump, and this morning proves it,” he claimed.
Carl Hulse and Matt Flegenheimer contributed reporting from Washington, and Trip Gabriel contributed from New York.