Republican Presidential candidate Ted Cruz will pick up his first Senate endorsement Thursday when Sen Mike Lee, a Republican from Utah, will announce he's backing Cruz, sources familiar with the decision tell NBC News.
The endorsement comes just days before key contests in Ohio and Florida, and it gives the Texas Republican momentum after winning Idaho on Tuesday and receiving the endorsement of former Republican candidate Carly Fiorina on Wednesday.
Lee was one of only three GOP senators who missed today's Senate vote on a bill to aid those affected by opioid abuse. The other two were Sens Rubio and Cruz.
While Cruz has become a divisive figure within the Republican conference in the Senate, Lee is considered one of his only allies, and at a recent campaign stop Cruz said Lee was "someone I love like a brother."
But Lee has not endorsed until today, instead choosing to campaign for both Cruz and Senator Marco Rubio, a Republican from Florida.
"I've got two really good friends in this race," Lee told reporters at a Cruz campaign stop in South Carolina in February, "Any one of them running alone would have gotten my endorsement a long time ago."
The endorsement of Cruz over Rubio before Tuesday's primary in Rubio's home state of Florida may be a sign that Republicans see Cruz as the candidate who has the best chance to combat Donald Trump.
Rubio's campaign has failed to meet expectations in recent weeks, and the Florida Senator was awarded zero delegates on Tuesday, when four states held contests in the Republican race for the nomination. While Rubio has the backing of 14 Senate Republicans, some of them publicly have express concern that he may need to exit the race if he fails to win Florida next week.
"I'm not going to give him any strategy or tell him what to do or what not to do, I'll let his people do that," Senator Dean Heller (R-NV), who has endorsed Rubio, told reporters, "But I think he's going to have to really rethink moving forward after Florida."
But Heller told reporters that if Rubio dropped out of the race he could see himself supporting Cruz if he became the nominee.
"Most certainly, most certainly," Heller said when asked if he could support Cruz, "I don't want to weigh in on who's best or who's not best, but I could see myself as a Cruz supporter."
"You know, as a supporter of Bush, and now a supporter of Rubio, I think the general public as a whole has been pretty convincing that they want something very different than what we have today," Heller said.
Sen Lindsey Graham, a Republican Senator from South Carolina who also ran for President this year before dropping out in December, said he believes Lee's endorsement of Cruz could help him show he's a viable alternative to Donald Trump.
"It shows that people see Ted's campaign as becoming the most viable," Graham told NBC News, "I just think he's becoming the most viable alternative to Trump."