Republicans begged, cajoled, and pleaded with Marco Rubio to change his mind and run for re-election.  

That the Florida senator actually agreed to do so is a stunning coup for the party. It also means the GOP’s chances of holding on to Rubio’s seat might still be no better than a tossup.  

Rubio ended weeks of speculation Wednesday when he announced he would try to return to the Senate in 2017. Republicans will tout the decision as one that could save their embattled majority, which can afford to lose a net of at most five seats in a year chock-full of blue-state GOP incumbents.  

[ Breaking: Rubio To Seek Re-election to Senate ]  

They might be right: Leading party strategists had publicly ridiculed the field of would-be Rubio replacements in Florida, convinced none of them could win a big-state seat in a tough environment. Rubio’s considerable political chops and national fundraising network at least guarantee the party a fighting chance.    

Fresh poll data released Wednesday, just hours before word of Rubio’s return leaked, also shows him leading either of his two Democratic opponents by a healthy margin.  

But the first-term lawmaker isn’t immune to the potential down-ballot fallout of Donald Trump’s presidential campaign, especially in a Latino-heavy state like Florida. Polls show Trump already trailing in the state badly.   

[ Rubio Says He Won’t Speak on Trump’s Behalf at GOP Convention ]  

And top-of-the-ticket concerns aside, Rubio has problems of his own. His failed presidential campaign exposed weaknesses — including missed votes and a professed disdain for serving in the Senate — that his Democratic foes now plan to exploit.  

Rubio’s Will-He Won’t-He Saga

In the eyes of Democrats watching the race, Rubio’s return hurts their chances of winning. It doesn’t come close to ending them.  

“If it was lean Democrat two days ago, it’s probably a tossup now,” said Steve Schale, a leading Democratic strategist in Florida. “But I don’t know that it’s any better than a tossup for Marco.”  

Democrats wasted little time before criticizing the incumbent for running for president instead of serving in the Senate. It’s a preview of coming attacks against Rubio, in which Democrats say they will make an issue of everything from his missed votes (an issue during his presidential run) to the possibility that he could make another go at the White House before his next term in the Senate ends.  

“Marco Rubio abandoned his constituents, and now he’s treating them like a consolation prize,” said Rep. Patrick Murphy, a Democratic Senate candidate who is the favorite to face Rubio in the general election. “Unlike Marco Rubio, I love working hard every single day for the people of Florida.”  

Even before he reaches the general election, Rubio must first fend off a primary. Rep. Ron DeSantis and Florida Lt. Gov. Carlos Lopez-Cantera, Rubio’s close personal friend, both announced they were leaving the race after Rubio’s announcement. Rep. David Jolly exited the primary contest last week.   

[ Senate GOP Candidate: Florida Voters Don’t Want Rubio ]  

But former CIA officer Todd Wilcox and Miami-area developer Carlos Beruff have each vowed to remain candidates, ahead of the state’s Aug. 30 primary. Beruff, in fact, has pledged to spend another $10 million to $15 million trying to win the seat, on top of the $4 million he has already invested on his campaign’s behalf.  

“This isn’t Marco Rubio’s seat; this is Florida’s seat,” Beruff said in a statement. “The power brokers in Washington think they can control this race. They think they can tell the voters of Florida who their candidates are. But the voters of Florida will not obey them. Like Marco Rubio in 2010, I’m not going to back down from the Washington establishment. They are the problem, not the solution.”  

Beruff added that “career politicians like Marco Rubio worry more about keeping the job than doing the job.”  

Based on name recognition alone, Rubio will start the race at a massive advantage over Beruff and Wilcox. And the two men, both of whom draw on their business background while touting their lack of experience in public office, could split the anti-Rubio vote.  

Still, Rubio’s presence adds clarity to a primary that was otherwise jumbled. And it shifts the onus back onto the Democratic primary, where Murphy and Rep. Alan Grayson are battling for the nomination.  

Murphy, who has the support of President Barack Obama and Senate Minority Leader Harry Reid, is the favorite in the primary. But any potential advantage he hoped to have over his potential GOP foes was erased when Rubio entered the race.  

“Whereas Marco Rubio is well-known to voters in Florida, nobody has ever heard of Patrick Murphy,” said Ian Prior, spokesman for the GOP-aligned super PAC Senate Leadership Fund. “That means Murphy and his allies are going to have to spend a ton of money to introduce him to voters, all while facing withering attacks from our side trying to win the race to define him.”

Contact Roarty at  alexroarty@cqrollcall.com  and follow him on Twitter  @Alex_Roarty .