The Republican Party will lose the White House, the Senate and many of its House seats if Donald Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE becomes the party's presidential nominee, according to Karl Rove Karl Christian RoveThe Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Sunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Chris Wallace: This isn't the GOP convention, 'it's really the Trump convention' MORE.

“If Mr. Trump is its standard-bearer, the GOP will lose the White House and the Senate, and its majority in the House will fall dramatically,” the Republican wrote in an op-ed for The Wall Street Journal.

ADVERTISEMENT

Rove, who was a top adviser to former President George W. Bush, said nominating Sen. Ted Cruz Rafael (Ted) Edward CruzThe Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Cruz blocks amended resolution honoring Ginsburg over language about her dying wish Trump argues full Supreme Court needed to settle potential election disputes MORE (R-Texas) for president could also be dangerous.

“If the nominee is Ted Cruz the situation is still dicey,” he wrote.

“Any of the other candidates, if nominated, will best Mrs. Clinton in a close race and help the GOP narrowly keep the Senate,” Rove added, referring to Democratic presidential front-runner Hillary Clinton.

Trump has repeatedly attacked Rove for doubting his campaign. He said last November that Rove is a “biased dope” who lost “100 percent” of the money he spent during the 2012 election cycle.

Rove's super-PAC, American Crossroads, spent tens of millions of dollars in 2012 trying to elect Mitt Romney president.

“I think Karl Rove still thinks Romney won,” Trump quipped Friday on “The Mike Gallagher Show.”

In his op-ed, Rove sketched out several scenarios in the op-ed that he says could stop Trump's ascent.

“If the GOP contest narrows to two or three candidates by March 15, Mr. Trump will not be the party’s nominee,” he wrote.

“If on the Ides of March someone wins both the winner-take-all primaries in Florida (by Congressional district) and Ohio (statewide), that person will be the nominee,” Rove added.

No matter who wins, Rove said the GOP standard-bearer would have an uphill battle against Clinton.

“It will be an ugly contest,” he wrote. "Mrs. Clinton will try to overcome her flaws by scorching her opponents."

“The FBI will recommend action against Mrs. Clinton’s former aides over her private email server, but not against Hillary,” Rove wrote.

Trump maintains a roughly 15-point lead over Cruz in national polls of the Republican race. The pair’s popularity has alarmed the GOP establishment, which fears that either one could be a weak candidate in the general election.gogol