This exchange between Sen. Marco Rubio (R-Fla.) and Bill O’Reilly neatly sums up the immigration debate:

Democrats have falsely accused Sen. John Cornyn (R-Tex.) of introducing a poison pill amendment to enhance border security. That accusation is demonstrably false (both because Rubio and Cornyn are working hand in hand and because Cornyn’s amendment sets reasonable and attainable benchmarks). But in his exchange with O’Reilly on Fox News, Rubio spelled out the true poison pill: Introducing the marriage issue into the bill.

He has made clear enumerable times that he won’t be able to drag Republicans over the finish line without something more on border security (that includes the magnets Republicans believe currently exist for illegal aliens). The bulk of gettable Republican senators who voted for cloture will not vote for the actual bill unless and until border security concerns are met and they feel confident this is the last time they will have to deal with the issue. If a senator is fixated on the gay marriage issue, he doesn’t want a passable bill. If he is determined to reject any further efforts to enhance border security, he doesn’t want a passable bill. From the other side, if he doesn’t want some pathway to citizenship, he doesn’t want a passable bill.

These are simple statements of political fact. Democrats need a pathway to citizenship while Republicans need a border security plan that in Rubio’s words guarantees the illegal immigrant problem doesn’t reappear. I could argue from now to doomsday that gay marriage is perfectly acceptable within the context of immigration reform or that the border provisions in the bill already with stringent protections to prevent illegal immigrants from working (i.e. take away the magnet) are sufficient. But whatever my own views, I can recognize what is doable and what is not. At some point Republican senators have to decide whether they would prefer to play to the crowd of anti-immigration advocates or really want to get this done.

In that vein, yesterday, Sen. Orinn Hatch (R-Utah) and Rubio introduced four measures to  get Republicans on board that clarifies what is already in the bill or assures Republicans the “lure” of public benefits will be eliminated in the future. A pro-immigrant Republican aide tells me that Democrats should embrace these since they are “totally consistent” with the Gang of Eight’s principle that federal benefits shouldn’t be given to illegal immigrants. In other words, the bill will need belt and suspenders on some items to take away excuses for not signing on.

In an e-mail Rubio’s office summarizes these changes:

Compliance with welfare, public benefits laws:  This amendment would prevent the Obama Administration from undermining welfare reform and ensure that no noncitizen will get welfare. Under S. 744, the prohibitions for federal means-tested public benefits, described in Title IV of the Personal Responsibility and Work Opportunity Reconciliation Act, such as cash welfare, are extended to Registered Provisional Immigrants (RPI), Blue Card holders and aliens admitted to the United States.  . . .

Payment of back taxes: This amendment would clarify the underlying bill to ensure that certain immigrant applicants satisfy their lawful federal tax obligations during any period of their U.S. residency by requiring that immigrant applicants must demonstrate to the Treasury Department (or Internal Revenue Service) that they have actually paid their back taxes, and continue to pay taxes.   . . .

Five-year waiting period for ObamaCare tax credits, subsidies: This amendment requires a five-year waiting period for individuals going through the RPI and Blue Card pathway when they become legal permanent residents for tax credits and cost-sharing subsidies under the Patient Protection and Affordable Care Act (PPACA).  The amendment simply aligns the five-year waiting period that applies to other federal means-tested health programs, like Medicaid and the Children’s Health Insurance Program (CHIP) to the premium tax credits and cost sharing subsides under PPACA. . . .

Prohibits Social Security benefits to unauthorized workers: This amendment helps protect the Social Security program by ensuring that those not authorized to work in this country cannot claim unauthorized earnings to gain eligibility for Social Security coverage, and stops the Social Security Administration, for the purpose of determining Social Security coverage, from counting taxes paid by unauthorized workers, including those who posted earnings using made-up or stolen Social Security numbers.

Understand that each of the amendments with which Rubio will associate himself is aimed at getting some segments of Senate Republicans.

The political reality is that it is important to get as many R’s on board even if a few D’s defect. That is because some political momentum is needed to keep the bill moving forward in the House. Ultimately the final bill will have to get hashed out in a conference. But failure or a skin-of-the-teeth win in the Senate will undermine those in the House who actually want a deal.

As for the White House, the president desperately needs a win on something and an issue other than the scandal-fest to dominate the news. If he actually understands the political dynamic he will urge the Dems to be flexible so long as the pathway to citizenship remains. If he, instead, is so obsessed with finding an issue with which to attack Republicans he will demand gay partners be included, oppose items that enhance border security and argue against efforts to make it arduous for illegal immigrants to obtain federal benefits.

It is time for both Republicans and Democrats to decide: Do you want a bill or a perpetual fight?

Jennifer Rubin writes the Right Turn blog for The Post, offering reported opinion from a conservative perspective.