Sen. Marco Rubio (R-Fla.) is a good politician but a bit of an open book. That is why it pays to listen carefully to what he says publicly about immigration reform.

He has very openly encouraged conservatives to improve the bill. In a statement released today, he again says that “in order for this bill to become law, it will have to be improved to bolster border security and enforcement even further and to limit the federal government’s discretionary power in applying the law. In addition, additional measures will be required to address potential costs to taxpayers.”

This we can surmise is not aimed at exclusionist dead-enders who, like Sen. Ted Cruz (R-Tex.), have let on that border security is a smokescreen for their core objection: They don’t want anyone legalized. Rather, we can assume he has gauged the lay of the land and figured out two factors.

First, the White House and Democrats are anxious for a deal, not any deal, but close. Their bottom line is that they just need a path to citizenship, unlike the most extreme activists who object to reasonable border control measures or guest worker plans. That means Rubio has running room to pick up additional conservative support from those who have limited concerns, yet still want immigration reform to succeed.

Second, there are a batch of conservative Republicans whose support is likely gettable by tweaking the bill to put belts and suspenders on the border triggers and wall off federal benefits from those who came here illegally (thereby disarming the “they only come here for welfare” cranks). So look to figures like GOP Sens. Orinn Hatch (Utah), John Cornyn (Tex.), Rob Portman (Ohio), Pat Toomey (Pa.), Mike Lee (Utah), Rand Paul (Ky.) and others to bend the bill to the right. If they do so, then the bill may garner a large super-majority.

If — and it is still a big if — liberals don’t then try to wreck the bill by overreaching and it gets to the House, the question remains whether reformers like Rep. Paul Ryan (R-Wis.) can point to the changes, saying reasonable concerns have been addressed. Then they will need to generate a bill that can pass the House and mesh with the Senate version.

Ironically, the flawed Heritage study has generated such a backlash from fiscal conservatives who cannot in good faith embrace the notion that fewer people make us richer or that every immigrant will be a poverty-stricken, ward of the state (and hence a drain on the Treasury) that it affords conservative reformers room to move forward, so long as they point to improvements in the bill. The need to resort to schlock economics and to misrepresent what is actually in the bill suggests that exclusionists’ appeal is limited and, unlike 2007, unlikely to dissuade conservative reformers who want to make immigration reform work better.

The key then to immigration reform is not the “not over my dead body” crowd (e.g. Heritage, Cruz and Sen. Jeff Sessions) but the mainstream conservatives in the House and Senate. For them, accurate polling, smart economic analysis and a deliberative legislative process matter. That is precisely why you’ll see more of all three in the weeks ahead.

UPDATE: The Tampa Bay Times confirms that this is Rubio’s outlook and approach to dealing with critics:

“[Heritage’s] argument is based on a single premise, which I think is flawed,” Rubio told reporters. “That is, these people are disproportionately poor because they have no education and they will be poor for the rest of their lives in the U.S. Quite frankly, that’s not the immigration experience in the U.S. That’s certainly not my family’s experience in the U.S. The folks described in that report are my family. My mother and dad didn’t graduate high school and I would not say they were a burden on the United States …  My parents were a lot better off 25 years after they emigrated here than they were when they first got here. And their children certainly have been. I still think we’re that country. And I still think we can be that country and even more in the future. So I guess I just have a lot more belief in the future of the country than some of the folks that helped prepare it.”

The report continued: “This afternoon, Rubio is holding a closed-door meeting with conservatives, part of his effort to gain support for the bill. He and other proponents realize they need a strong showing in the Senate (though 70 votes seems a high bar) to provide momentum as the House takes up the debate.” And Rubio made clear he’s distinguishing between Republicans who want to be constructive and those who don’t: “For members of the Senate Judiciary Committee, this is their first chance to make a good faith effort to improve the bill. I look forward to working with them throughout this process to ultimately fix our broken immigration system. . .  . Anyone who opposes this bill but fails to offer a real and specific alternative is in favor of the status quo. And the status quo is de facto amnesty.”