Marco Rubio’s decision to run for re-election to his U.S. Senate seat, which he announced Wednesday morning, gives Republicans a boost in their bid to retain control of the Senate. But it also sheds light on how Rubio views his political future and how Republican Senate candidates in swing states might act toward Donald Trump.

The decision made sense from the party’s point of view. Rubio led both possible Democratic candidates for the Florida seat (Alan Grayson and Patrick Murphy) in a Quinnipiac University poll released this week. At the same time, both Democratic candidates were ahead of all the possible Republican challengers, including a businessman, Carlos Beruff, who is staying in the race even as Rubio enters it. Looking back at the simple model that I put together at the beginning of June, Rubio has a 73 percent chance of winning re-election, compared with the 36 percent chance Republicans had at holding the seat before he got back in.

Of course, 73 percent is not anywhere close to 100 percent. There is a decent chance that Rubio’s lead could evaporate in the general election, especially as his eventual Democratic competitor becomes better known. And although Rubio will probably win his primary to advance to face the Democratic nominee for Senate, the fact that Rubio has already lost one Florida primary this year (i.e. the presidential primary) suggests that he shouldn’t take anything for granted. So why has Rubio decided to take the plunge and potentially suffer his second loss this year, which could tar him for life as a political loser?

Rubio, who many believe wants to run for president again, judged the terrain and apparently decided the best way to compete in a future presidential primary was to remain a member of the Senate.

If Rubio had not run, he was faced with two possible options. The first was becoming a private citizen. That isn’t necessarily the worst thing in the world; recall that, Mitt Romney won the 2012 Republican nomination even though he had not held office since 2007. Rubio, however, would probably face a very competitive primary for president in 2020, with potential competitors like Ted Cruz (who lasted longer than Rubio did in 2016), Scott Walker, or even a new candidate like Tom Cotton. Unlike those candidates, private-citizen Rubio wouldn’t have a platform to articulate his message. He would be nothing more than the guy who used to hold a Senate seat and ran for president and lost. Winning in 2016 would give him a soapbox and some redemption for losing.

The second option was running for governor in 2018. That position would be better than senator if he wanted to position himself as an outsider, which Republicans seem to love these days (see Trump, Donald). But there was no guarantee of him winning that race, and even if he did, he would have to start running for president right after winning the governor’s mansion. That’s a tough sale to voters, and I’m not even sure a politician like Rubio, who reneged on his word not to run for Senate in 2016, could possibly run with a straight face in 2018 with the understanding that he would try for the presidency again in 2020.

Rubio instead decided that he could win in 2016, even with Trump at the top of the ticket. Rubio seems to be betting that he can run as the anti-Hillary Clinton and the anti-Trump to some extent. In his statement announcing why he was going to run for the Senate, Rubio bashed Clinton and called Trump “worrisome.” He wants voters to see him as a check on both of Clinton’s and Trump’s powers. Moreover, Rubio is “willing to encourage [Trump] in the right direction” if he becomes the president.

Can that strategy work? I’m not sure, though it has a shot. Both Clinton and Trump are unusually unpopular candidates who happen to have the advantage of running against each other. It’s possible that both of them are so unpopular that there won’t be the usual coattails that we’ve seen in recent Senate races. It will be interesting to see whether candidates in other swing states (not just blue states like Illinois, where Republican Sen. Mark Kirk is up for re-election) take up Rubio’s mantle of trying to act as a compromise candidate between Clinton and Trump.

The other question I have is whether Rubio and other Republicans can be against Trump without being too against him. Trump was popular enough to become the presumptive nominee, and many Republican voters in a future presidential primary might be unwilling to forgive a politician who came out too harshly against Trump and allowed Clinton to win the presidency. At the same time, there’s a sizable anti-Trump constituency in the Republican Party, even if it is a minority. That minority may become larger if Trump gets blown out in 2016. Rubio, like other Republicans running this year or in the near future, needs to be able to thread that needle.