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Donald Trump changes tune on man who "couldn't get elected dog catcher in Florida"

Donald Trump, who once said Sen. Marco Rubio "couldn't get elected dog catcher in Florida," is now pushing his former opponent to run for Senate re-election in the state.

Trump sent a tweet late Thursday encouraging the Florida senator, who has said he would not run for a second term, to help "keep the MAJORITY" for Republicans in the upper chamber:

That's all despite Trump's long Twitter history of insulting Rubio -- once a rival for the Republican nomination before the Florida senator exited the race in March -- as a "joke," a "choker," and a "dishonest lightweight" who was "scamming Florida" while running for president.

Trump's recent social media turnaround is a reflection of Republican concerns on Capitol Hill, where party leaders are increasingly anxious about the GOP hold on Rubio's Senate seat. The cutthroat Republican primary unfolding between five candidates, some lawmakers fear, could diminish the party's chances against Democrats in November's Senate contest.

After laying out worries over the Florida Senate race during a private lunch Thursday with other GOP senators, Majority Leader Mitch McConnell surveyed who in the room wanted Rubio to reconsider his decision to opt out of a re-election bid.

According to a Politico report, virtually all the attendees raised their hands.

Other Republican lawmakers also publicly echoed Trump's latest refrain, including Tennessee Sen. Bob Corker, chair of the Senate Foreign Relations committee.

Rubio campaign: Donald Trump is a bully

On the Senate floor Thursday afternoon, Corker said he "strongly encouraged" Rubio to seek re-election. He followed that up with a statement later that day, where he praised the Florida senator as a "very valuable member of the Senate -- especially in his role on the Senate Foreign relations Committee, where he demonstrates a deep understanding of foreign policy."

And on CNN, Sen. John Cornyn of Texas, the Senate's No. 2 Republican serving as the party's majority whip, said he'd "like to see" Rubio reconsider.

"It's obviously a very personal decision, but I think it would be good for the party. It would be good for the Senate. I'd like to see him do it," Cornyn said Thursday. "I hear a lot of buzz around here from members and others -- that's a conversation we need to have."

For his part, Rubio told reporters Thursday that it was "unlikely" he would enter the Senate race so late in the game.

"I didn't think it was fair for me to run for president and freeze that seat in a competitive state. So I made my decision," Rubio said. "I don't have anything new to say from what I said in the past... I made that decision and I've lived by that decision. Nothing's changed."