Republican front-runner Donald Trump likes to mock Ted Cruz for not having received a single endorsement from a fellow member of the U.S. Senate. That mocking ends today, as Utah Senator Mike Lee will endorse the Texas senator in Miami, Fla.

The endorsement comes as a blow to Florida Senator Marco Rubio, whose campaign is struggling after winning only two primaries (one in the territory of Puerto Rico, not even a state), and running behind Cruz in nearly every contest so far. Calls for Rubio to exit the race and endorse Cruz even interrupted a Miami rally yesterday, which had a significantly smaller crowd that earlier Florida rallies this year.

Senator Mike Lee is considered a Tea Party conservative stalwart. Due to his close connections with both Cruz and Rubio, Lee delayed his endorsement to avoid potentially alienating one of them. Last year, he sat down with Rand Paul (then a presidential candidate), Rubio, and Cruz, and said, “Look: I’m in an awkward spot because I’m really close to all three of you guys.”

As late as December, Lee declared that “one of the weirdest things that can happen to a person is to have his three favorite co-workers all running for president of the United States at one time. It’s just weird.”

Cruz has come under fire for being unpopular among elected Republicans, but signs are increasing that elected leaders are accepting that his campaign may be the only one strong enough to block a Trump nomination. Meghan McCain, daughter of Senator John McCain — whom Cruz has attacked numerous times as being a spineless Republican-In-Name-Only — recently endorsed Cruz, as did Neil Bush, brother to George W. Bush and Jeb Bush.

After Lee’s endorsement, some expect more outspoken conservatives, like Nebraska Senator Ben Sasse, to rally around the Texas senator. Expect more surprises in the coming weeks.