Senate Republicans who have not endorsed former President Trump acknowledged on Wednesday that his New Hampshire primary win makes him the likely GOP nominee.

Why it matters: It's a blow to former UN ambassador Nikki Haley as she faces increasing pressure from top Republicans in Congress to step out of Trump's way.

What they're saying: Senate Minority Whip John Thune (R-S.D.), who previously supported Sen. Tim Scott (R-S.C.), said Trump is in a "commanding position" and is "sure looking" like the presumptive Republican nominee.

• "I think Nikki Haley ran a very good campaign ... but it is pretty clear Donald Trump is going to be the nominee," said Sen. Mitt Romney (R-Utah).
• "I think if you look at it, Gov. Haley's going to stay in the race and there may be some competitive primaries, but I think he's got it mapped out at this point," said Sen. Thom Tillis (R-N.C.).
• "[Trump] rolled, it looks like. It's a big victory for him," said Sen. Shelley Moore Capito (R-W.Va.).
• "I think, essentially, the primary is now over," said Sen. Rand Paul (R-Ky.).

The other side: Sen. Susan Collins (R-Maine) said it's "too early to say" if he is the presumptive nominee.

• The New Hampshire result was "not surprising in that he was projected to win," Collins told Axios, adding that Haley "nevertheless had a good showing and showed her appeal across various demographic groups."
• "We have a long ways yet to go. The one thing I've learned is in campaigns, the unpredictable can happen at any time."

The intrigue: Despite Trump picking up endorsements from Sens. John Cornyn (R-Texas) and Deb Fischer (R-Neb.) on Tuesday night, none of the other skeptical GOP senators said they are prepared to endorse him yet.

• "I haven't come out and endorsed anyone. I didn't in 2016 either," said Sen. James Lankford (R-Okla.).
• Paul, who has declared himself "Never Nikki" due to her interventionist foreign policy, said he is "still thinking about how much I'm going to be involved in the presidential race," but is "obviously not opposed" to Trump.

What we're watching: While some, like Tillis and Sen. Chuck Grassley (R-Iowa), told Axios they will support the eventual Republican nominee, others firmly ruled out ever endorsing Trump.

• Sen. Todd Young (R-Ind.) said he has "no intention" of supporting Trump.
• "I have said that I am not endorsing President Trump," said Collins – who added she also won't endorse Haley due to a neutrality policy she adopted early in the primary "when I had so many friends that were running."
• Romney, asked if he would ever endorse Trump, replied "no, no, no," noting that he voted to convict Trump in both his impeachment trials: "How could I possibly endorse someone who I voted [committed] a crime or misdemeanor?"