Donald Trump’s stirring primary victories in South Carolina and New Hampshire are a moment of truth for the Republican establishment, who now have to decide if it’s time to rally against the mogul — possibly strengthening his contrarian appeal with voters — or find common ground and unify behind him.

“He’s got them in a real Sophie’s Choice,” said Patrick Griffin, a Republican media consultant whose clients have included the campaigns of presidents George H.W. Bush and George W. Bush. “I think there’s a whole lot of soul-searching going on right now in the party, as to if they wish to deal with Trump now or deal with him later. Because one way or another, Donald Trump is not about to toe the line. That’s one of the things that made him attractive to voters.”

Fergus Cullen, a former chairman of the New Hampshire GOP, said, “You can’t negotiate with terrorists, and that’s what Donald Trump is to the Republican Party.”

Trump is favored in the next GOP primary in Nevada, but the slate of Super Tuesday primaries on March 1, including Massachusetts, could either strengthen or weaken his grip on the nomination.

Rod Benfield, a Ted Cruz supporter and GOP operative from South Carolina — where Trump defeated runner-up Marco Rubio by 10 points on Saturday — said he expects Republicans to “circle the wagons” to counteract Trump, likely with Rubio leading the charge.

“They are not ready to give it to Trump,” Benfield said. “They’re just rallying around Rubio, and you’re going to see more and more. … Even if you get through Super Tuesday, there’s still delegates out there to be to be had. It’s a marathon. There’s no way the political pundits or the media could call this thing and say, ‘Trump’s got it.’ It’s way from being over.”

After March 1, the key delegate-heavy states in play include Florida and Ohio. Rubio, a U.S. senator from Florida, is very popular in the state’s most populous areas, and an endorsement from an on-the-ropes John Kasich could make all the difference in Ohio, where he is governor.

Cullen, a Kasich supporter, said he could see an early formation of a Rubio/Kasich ticket to dent Trump’s momentum.

“It may come to presenting Republican primary voters in future states with a choice where two of the candidates team up and say, ‘Look, if I win, this is going to be my running mate,’ ” Cullen said. “Could you imagine Kasich and Rubio getting together, for example? And saying, look: To the two-thirds of the party who would not support Trump, if you want to stop Trump — and we all do — it’s a simple choice.”

Cullen thinks there’s little chance the Republican Party will ever coalesce around Trump, saying his “views are abhorrent,” and associating with them could hurt some GOP senators — whose constituents might be much more sensitive to Trump’s irascible nature than national voters — in their own elections this year.