As an immigration reform bill heads to the floor of the Senate, Sen. Marco Rubio (R-Fla.) is staking out a position as the guy who can help bargain for Republican votes.
The bipartisan legislation will likely only need a handful of GOP votes to gain passage in the Democrat-controlled Senate. But the senators who drafted the bill want to pass it with a strong majority.
See Also: George W. Bush on Immigration
The reason: They think that will help its chances in the House, where Republicans have the majority and guys like Rep. Steve King (R- Iowa) will be scheming to kill it.
That's where Rubio comes in.
Even though Rubio is one of the authors of the bill, he's suggested changing it in recent weeks. That's because he thinks certain parts to the legislation need to be altered if it's going to pass, according to Alex Burgos, a spokesperson for the senator.
The bill will have to "earn the support of Democrat and Republican senators who do not support the bill as it stands today," Burgos wrote in an email.
So far, Rubio has mostly been working to pick up Republican support. Take border security, for example.
As the legislation stands right how, the U.S. Department of Homeland Security is tasked with coming up with a plan to secure the border. Rubio suggested on Fox News recently that it might be better for Congress to spell out how the plan should work.
"What people are saying is, we don't trust the Department of Homeland Security to come up with a good border plan, we don't trust the Department of Homeland Security to come up with a good fencing plan, and so maybe the alternative is to have the Congress do that," Rubio said. "The point is that needs to happen. That is the lynchpin of whether this will work or not."
Rubio's mission to make the bill more conservative might be necessary to help it's long-term odds at passage. But it could also agitate liberal supporters of immigration reform, like Frank Sharry, the executive director of the immigration lobbying group America's Voice.
"Rubio is uniquely qualified to talk to conservatives about immigration reform," Sharry told Reuters. "On the other hand, if he thinks now that he's the face of immigration reform, that he's going to drive this bill in a direction that makes it less palatable for the progressive coalition that created the political space for reform, it's going to be a huge problem."
It's the price Rubio pays for sitting at the center (or center-right) of this coalition. He's the glue holding the deal together, but that's also made him a popular target for both sides.
Some immigrant rights groups are already going after Rubio for things like beefed up border security. See this protest on Friday at his Florida office for a taste.
And at the same time, he's been weathering attacks from immigration restrictionists who are angry that he's supporting citizenship for undocumented immigrants. Those seem to be growing in intensity, with one group reportedly taking out 30-second ads against the senator on Florida television.
What this means is that he'll be the politician to watch as the debate moves forward, even if you're watching in frustration.