Hawkish Sen. Tom Cotton of Arkansas, the youngest senator, has no plans to endorse; Huckabee’s withdrawal could have liberated Cotton to come off the sidelines. Sen. Mike Lee of Utah is “not a fan” of Trump and speaks fondly of both Cruz and Rubio, but he isn’t yet planning to insert himself into the race, either, an aide said.

It’s not that any one endorsement will put Rubio over the top. But a rush of support on the heels of Rubio’s top tier performance would mean “validating the momentum” of the first-term senator’s campaign, said Sen. Cory Gardner (R-Colo.).

“How much louder do the quiet rumblings for Rubio become? Because over the past several months since I endorsed Rubio, a lot of people come up and say, ‘Thanks for doing this. Thanks for going to Iowa for Rubio,’” Gardner said, “Does that become a public conversation and turn into an endorsement?”

The answer in the immediate aftermath is: not yet.