Update: Rubio is now in, The Post is reporting. And right on time, Quinnipiac University is out with a new poll of the race. Rubio leads Rep. Patrick Murphy, the favorite for the Democratic nomination, 47-40. He leads the more liberal and controversial Rep. Alan Grayson by basically the same margin, 48-40.

It's worth noting that Rubio's approval/disapproval split is slightly better than the last time Quinnipiac polled, in May, but Floridians are still split on him, with 45 percent approving and 44 percent disapproving. He also likely benefits from superior name ID against both Murphy and Grayson. Expect a close race, particularly if his opponent is Murphy.

The below post runs through more of the race's particular. It is from last week.

We can't definitively say this, but it looks more and more like Sen. Marco Rubio (R-Fla.) is going to reverse course and run for reelection. At the least, he's now publicly considering it and says he's talking it over this weekend with his family.

An even tougher question at this point might be this: Will he win? Indeed, it's entirely possible Florida's Senate race will be a tossup with or without Rubio, despite the official Republican Party tripping over itself to get the former presidential candidate back in the race.

If Rubio does jump back in, we can expect plenty of upheaval in the GOP primary. At least three of the five credible candidates, such as Rep. David Jolly (Fla.), are expected to step aside to make room for Rubio. But two outsiders with lots of money say they'll stay in.

Senate Republicans think a Rubio candidacy will help them keep the Senate majority because, well, they think Rubio could win a state that without him was trending in the wrong direction.

But a Rubio reelection bid hardly takes this race off the table. He's simultaneously not that well-liked among Florida voters and being told by Florida Republicans that he's the only guy who can save them. It's a lot to consider.

Here are Rubio's challenges and strengths in a reelection battle, all of which lead us to the conclusion that we don't yet have a conclusion on whether he's a clear favorite — or even a favorite — to win.

The challenges Rubio will have to overcome

His now-defunct presidential campaign could be a problem. An editorial in one of Florida's largest newspapers called on Rubio to step down. Florida didn’t even vote for him in its presidential primary; he lost by 19 points, in fact. He looked less than senatorial when he got into a debate with Donald Trump on the size of Trump’s hands. Then there's that robotic debate performance in February. None of these events alone is disqualifying, but taken together they could paint a picture of a candidate who has fallen far short of the hype surrounding him.

He said he won't run. Repeatedly.

Rubio has sometimes couched that comment with "maybes" and "if it's the right fit." But Democrats can make the case Rubio is doing the exact opposite of what he said — an ambivalence that's not exactly confidence-inspiring.

Orlando. If Rubio gets in, it would be a week or so after the deadliest mass shooting in U.S. history, which happened in his state. (It would be at most two weeks; Florida's filing deadline is June 24.) Rubio could certainly frame his candidacy as a decision brought on by the tragedy and a calling to serve his country when it's hurting. And his foreign policy experience would probably play well in Republican circles right now, which tend to frame Orlando around terrorism rather than LGBT or gun rights.

But we can just as easily see how Democrats could cast Rubio as an opportunistic politician taking advantage of a tragedy for his political benefit. Either way, Orlando could be a tricky line for Rubio to walk.

His approval rating isn't great. A May Quinnipiac poll pegged his approval rating at 42 percent, with 49 percent disapproving. Again, not disqualifying, but not a great start for a statewide race, either. Those are the numbers of a politician who would be fighting hard to keep his job.

Donald Trump. Trump beat Rubio badly in the state's March 15 presidential primary. And now Rubio could be sharing the ballot with Trump, a guy who is hugely unpopular among a broader electorate of women, millennials and minorities — a swath of whom Rubio needs to win in this swing state. If those factions don't want to vote for Trump, Rubio's election hopes could be in trouble, too. The phenomenon of split-ticket voting is at its lowest in recent decades, as our own Philip Bump recently showed.

A loss might be game over for his career. Rubio hasn't ruled out running for office down the line. But if he runs now and loses, it could be game over, said Florida political analyst Susan MacManus: "A lot of Florida Republicans really like Rubio, but they are also worried if he loses in the general, then that's the end of him politically."

The reasons we could see a reelection bid working out for Rubio

Senate Republicans want him to run. None other than Senate Majority Leader Mitch McConnell (R-Ky.) has urged Rubio to run for reelection. So have a bunch of other Senate GOP leaders. That Rubio has fans in some very powerful places who are willing to help him get reelected counts for something (though perhaps less so in the Year of Trump).

Lots of Republicans want him to run. A recent Florida-based polling firm, Mason-Dixon, indicated that almost half of the state's voters — including  77 percent of Florida Republican voters — want Rubio to run again. That might suggest that for Florida GOP voters, some of Rubio's potential pitfalls pale in comparison to the lackluster field they've got right now. At the least, it suggests he'd have little trouble securing the GOP nomination, if there were any doubt about that.

He can bring in money. Florida is one of the most expensive states in the nation to run a statewide campaign; there are 10 media markets candidates have to play in. Rubio, having just run a national presidential campaign, is a proven, successful fundraiser. Senate Republicans hope that if Rubio gets in, in addition to improving their chances in Florida, they could spend their time and money elsewhere in their arduous battle to keep control of the Senate. (Caveat here: The two candidates who have indicated they'll run against Rubio in the primary are wealthy and seem willing to spend it to get their names out there.)

Some polls show him winning. Republican insiders are circulating polls that show Rubio easily winning the primary and then defeating both of his potential Democratic opponents, Reps. Patrick Murphy and Alan Grayson, by large margins (Murphy is far preferred to Grayson by Democratic leaders). Democrats cite an automated Democratic-leaning poll that shows Rubio basically even with Murphy but, among voters who have heard of both candidates, losing by 22 points in a hypothetical matchup.

We're citing this conflicting data because it proves that data alone can be tricky to pull conclusions from. General-election polling is faulty when there are still so many hypotheticals about who will actually be in the general election — let alone who's in the Aug. 30 primary.

What's pretty clear right now is that Rubio's entry in the race isn't a panacea for Republicans' attempt to hold on to his seat. Nothing's a given here, and it's entirely possible that Florida's Senate race will still be a highly contested one with or without Rubio.