“It fills all of us with concern and dread,” said Senator Jeff Flake of Arizona, who has endorsed fellow Senator Marco Rubio of Florida, considered the main hope of the Republican establishment to derail Trump’s march to the nomination.

Trump has vowed to scrap U.S. trade deals, slap a tariff on imported goods and raise taxes on hedge-fund managers, as well as retain some sort of mandate to purchase health insurance – clashing with the free-market principles that have long underpinned Republican economic policy.

Some Republicans in Congress, such as Flake and Senator Lindsey Graham of South Carolina, said a Trump nomination would do enormous damage to the party and predicted a heavy election defeat in November to the eventual Democratic nominee.

“I am like on the team that bought a ticket on the Titanic after we saw the movie,” said Graham, contending that Trump would be “slaughtered” in the general election.