Florida Sen. Marco Rubio (R). (Getty Images)

Sen. Marco Rubio (R-Fla.) is officially in for the 2016 presidential race, telling the Associated Press that he feels he is "uniquely qualified" to run and serve.

And Rubio is nothing if not unique in today's GOP. He's young (43 years old) in an increasingly old party, he's Hispanic in a party that is hemorrhaging Latino votes, he's a very good communicator in a party that struggled to find one in 2012, and he has ties to both the tea party and the party establishment in a party that is very much split between the two. And as we've argued before, he has more upside than just about anybody in the 2016 race -- Republican or Democrat.

[Marco Rubio: The ‘upside’ candidate of 2016]

He's also putting a lot more on the line than just about anybody else. For a few reasons:

1) He's giving up his Senate seat

Sen. Rand Paul (R-Ky.) is also running for president and, like Rubio, is up for reelection in 2016. But because Paul comes from a red state and the filing deadline for his seat isn't till late January 2016, he could potentially revert to staying in the Senate if his presidential campaign doesn't catch fire.

Rubio doesn't have that luxury. He comes from Florida, a big swing state in which you need to be focused on that race from day one. Democrats already have a solid contender in Rep. Patrick Murphy, and other Republicans are already looking at running for Rubio's seat.

The filing deadline in Florida isn't till May 2016, so Rubio could conceivably attempt what Paul is doing -- he hasn't quite ruled it out, though he came close -- but national Republicans can't really afford to let Democrats get that much of a head start in a very important state while Rubio figures out whether he can win the GOP presidential nomination.

All the other GOP hopefuls either aren't up in 2016 -- Wisconsin Gov. Scott Walker and Sens. Ted Cruz (R-Tex.) and Lindsey Graham (R-S.C.), for instance -- or are out of office altogether.

Rubio, as the youngest GOP hopeful in the field, is the only one giving up a bird in hand for the possibility of two in the bush.

2) That VP thing isn't looking so likely anymore

Well it doesn't matter if he doesn't win the nomination, you might say, because he's got a really good shot at becoming the vice presidential pick. This makes complete sense; with Republicans likely to nominate another white man and likely to face the potential first female president, getting some diversity on their ticket will be key.

And nobody fits the bill better than Rubio. Some are even joking about Rubio running for VP:

But the idea that Rubio could run for president with being VP as a backup plan took a significant hit the day Jeb Bush started running for president. That's because the fellow Floridian is perhaps the likeliest (if not likely, period) nominee, and the Constitution basically precludes him from picking Rubio as his running mate.

It says that no state can cast its electoral votes for a ticket that includes to people from their own state. And given Florida's 29 electoral votes are, well, kind of important, it's really hard to see Bush picking Rubio -- unless one of them conveniently established residency outside the Sunshine State.

In short, at this point Bush seems like the most likely nominee, and Rubio the most likely vice presidential pick, but Bush won't pick Rubio.

3) He has a lot more time

Rubio's youth also means he has more time to wage a political comeback, yes. But there are no guarantees in a state like Florida, and winning office is much more difficult than holding an office you already inhabit.

What's more, the Republican bench in Florida is teeming with ambitious young pols, by virtue of the GOP dominance of the state. The GOP controls all statewide offices and about two-thirds of the state legislature.

No, Republicans haven't exactly fielded the greatest candidates in recent years (Connie Mack, much?), but there are lots of new faces these days. That means that, if this whole 2016 thing doesn't pan out, Rubio can't count on returning to statewide office in Florida any time soon. Rubio would certainly be a frontrunner, but he would probably have to fight for it.

Time works both ways. Yes, Rubio would have years to mount a comeback. But it also means he has time to wait for another presidential campaign -- one in which he wouldn't have to give up his seat in the Senate to run.

And yet, he has chosen to strike while the iron is semi-warm and risk his political future on running for president.

What's clear is that he doesn't enter into it lightly.

Update: Longtime Florida political reporter Adam Smith tells our own Fix Boss about the reasoning for Rubio's move:

A lot like Jeb Bush, Rubio is an impatient guy. It was always hard to see him as a lifer in the Senate. Nor has he shown much enthusiasm for the slow, nuts-and-bolts work of actually legislating. He's more about announcing big policy ideas than actually crafting bills and corralling votes to implement them.

Personal finances, I think, probably also played a role. Four kids in private school, and living in both west Miami and D.C. is not easy financially.