What will Marco Rubio do?

Sen. Marco Rubio is coming under heavy pressure inside and outside the Beltway to change his mind and run for reelection to the Senate.

For Senate GOP leaders, the move is a political no-brainer.

{mosads}Rubio is a known quantity and an able fundraiser, and they believe he represents their best shot at keeping his Florida Senate seat in the Republican column.

For Rubio, the question is tougher.

Running for the Senate would be a significant political U-turn. He’s repeatedly railed against the ineffectiveness of the upper chamber and brushed aside questions about his lax attendance record.

He could also be risking his political future on a Senate race that Democrats view as a prime pickup opportunity and is widely as rated a toss-up.

Rubio is expected to make another run for the White House a soon as 2020, and a loss in November could undercut any future presidential aspirations.

He would also face a fight from within his own party to retain the seat. Five GOP candidates are vying to replace Rubio, including Lt. Gov. Carlos López-Cantera, who the Florida senator has repeatedly described as a “close friend.”

Democrats also have a contested primary in the Sunshine State. Rep. Patrick Murphy, who is backed by the party establishment, faces a challenge from the left by Rep. Alan Grayson.

Michael McDonald, a professor at the University of Florida who studies voter participation, said that Rubio might be the best GOP candidate. But a victory by the former presidential candidate would be no sure thing in an election with Donald Trump as the party’s presidential nominee.

“I would expect that it would be a close election. I don’t think he’s a shoo-in to win,” McDonald said. 

Rubio’s decision has huge implications for both parties.

The GOP has a tough task in defending 24 Senate seats across the country to hold on to its majority. Democrats need to gain just four seats and retain the White House to win back Senate control, and several GOP seats are toss-ups. 

Rubio has sidestepped questions about what he would do if López-Cantera dropped out of the race, something the Florida official has shown no signs of considering.

Courtney Alexander, a spokeswoman for the López-Cantera campaign, pointed to a recent article on news website Heat Street about Rubio doing a fundraising call with the lieutenant governor. Two sources told the website that “Rubio was on the call to make it clear that he was not running for reelection” and to raise financial support for López-Cantera.

Democrats are taking early shots at Rubio amid the speculation.

“Republicans may be publicly begging Marco Rubio to run for re-election and to save them from the “nightmare” cast of candidates they currently have, but if Rubio even were to run, his prospects in November — that is if he can make it past the primary — don’t look too promising,” the Democratic Senatorial Campaign Committee said in a statement.

That hasn’t stopped GOP leadership and strategists from vocally nudging Rubio to change his mind. Majority Leader Mitch McConnell (R-Ky.) acknowledged he and his Senate GOP colleagues have been privately pressuring Rubio to run for reelection.

“We’re all hoping that he’ll reconsider, because poll data indicates that he is the one who can win for us,” he told conservative radio host Hugh Hewitt this week.

Sen. John Cornyn (R-Texas), McConnell’s second in command; Sen. Roger Wicker, the head of the Senate GOP campaign arm; and Trump, the presumptive GOP presidential nominee and former Rubio nemesis, have all called on Rubio to get into the race.

Rubio would face a herculean task in building a late-entry campaign from the ground up. That would include raising Florida’s $10,400 qualifying fee for entering race, in addition to the millions he’ll need to compete in the expensive battleground state.

But his renewed presence in the Senate and refusal to shut the door on a reelection bid is only fueling public speculation.

Asked what he would do if party leaders made the case that he was the only GOP candidate who keep the seat in the Republican column, Rubio demurred.

“Well, like I said, guys … this is just something that happened today and, for me, I haven’t even had time to even talk to anybody about it, but my sense of it is nothing has changed,” Rubio told reporters late last month.

Rubio and his staff have repeatedly dismissed speculation about this or him running for governor in 2018.

Instead, the Florida Republican says he’ll become a “private citizen” as of January 2017.

Rubio, who said last year that he cashed in a retirement fund, has hired a lawyer to help him sort through post-Congress job offers, though he’s reportedly not interested in working for Wall Street or a lobbying firm.

It’s a stark contrast from Sen. Ted Cruz, who Rubio could face in a presidential rematch if he makes another bid. The Texas Republican is already getting 2020 speculation, and, unlike Rubio, he plans to run for reelection to the Senate in 2018.

Rubio, however, dismissed speculation about his political future during a late-night Twitter rant last month.

“Well it’s nearly impossible for someone not in office to ever become a successful candidate for President. Right?” he said at the time.