Sen. Marco Rubio exited the race for the Republican nomination on Tuesday, and now sources familiar with both Rubio and his rival candidate, Sen. Ted Cruz, indicate that an endorsement is in the works.

Those sources told Politico that Cruz will have to ask Rubio for the endorsement and both will have to determine if news of Rubio-endorses-Cruz will effect the outcome of the Republican presidential nomination. An anonymous adviser to the Cruz campaign, quoted in the report, revealed that conversations were going on with “Rubio’s people” and that Cruz would welcome a Rubio endorsement.

In the course of the campaign, Rubio was often criticized for an absentee presence in the Senate. Politico noted his return to work in the Capitol on Thursday. He told reporters on the Hill that he didn’t have any announcement on an endorsement “today,” while suggesting he may have one soon.

Also on Thursday, a group of never-Trump conservatives met in a closed-door meeting. Pressure may continue to increase for Rubio to endorse Cruz in an effort to block the frontrunner’s nomination.

Even establishment figure Sen. Lindsey Graham is reluctantly supporting Cruz. Stopping short of an explicit endorsement, Graham is holding a fundraiser for Cruz on Monday.

Also, Rubio told his Minnesota backers on Wednesday that he sees Cruz as “the only conservative left in the race,” according to the Twin Cities Pioneer Press. He emphasized hopes that one of the remaining candidates — Ohio Gov. John Kasich and Sen. Ted Cruz — will overtake frontrunner Donald Trump for the nomination. Rubio also blamed the national media and attack ads from former candidate Jeb Bush’s super PAC for the downfall of his positive campaign.

Rubio suffered a crushing loss to frontrunner Donald Trump in Florida in the March 15 primary, 45 percent to 27 percent.

Follow Michelle Moons on Twitter @MichelleDiana.