The border security amendment was still being drafted late Thursday night. Republicans could still balk and Democrats might still relish the prospect of wrecking the deal and blaming the Republicans. But provided the specifics are ironed out by staff, I would expect a significant number of Republicans to sign on. If so, it would be a momentous step for the Senate, the only true bipartisan effort of the Obama era (made possible only because he stayed out of it), if the Gang of Eight plan as amended passes with a large majority.

Sen. Marco Rubio (R-Fla.) (Alex Wong/Getty Images) Sen. Marco Rubio (R-Fla.) (Alex Wong/Getty Images)

A big win for the Gang of Eight would potentially have long-range consequences for the conservative movement and for the GOP, starting with these:

1. Success for the Gang of Eight would make Sen. Marco Rubio (R-Fla.) — whose popularity has only increased during the immigration battle — one of the titular heads of the GOP. He and a new generation of more reformist Republicans would have pulled off a major coup, in large part because of fiscal conservative and libertarian leaders on the right (e.g. Sen. Jeff Flake, Cato Institute, Americans for Tax Reform).

2. Sen. Rand Paul (R-Ky.) will likely not be among those voting yes and will once again be in the only role in which he can fully embrace — as an outsider, nonplayer who eventually votes “no” on most everything. His rhetoric on growing the party and reaching out to Hispanics will seem pretty empty. Even libertarians (as noted above) will have parted company with him. Exactly what is his niche in the GOP? You got me.

3. The phalanx of the most extreme radio talk show hosts, action groups and right-wing bloggers would, as they did in the 2008 and 2012 presidential nominating contests, come up short if the Gang of Eight plan passes with a comfortable majority. The party certainly does seem to have its ballast further to the center then they imagine. Would the more strident figures on the right clue in that they don’t really represent the party as a whole, or would they devise some “betrayal” scheme to explain the mass defection to the pro-immigration side?

4. Talk of the “broken system” and need for the “nuclear option” in the Senate could very well dim. Maybe the problem is not the Republicans or even the Senate rules, but the president. Without him, old fashioned legislating can take place.

5. Reince Priebus and those in the Republican National Committee who worked on the “autopsy” after the 2012 loss would have some vindication if the Gang of Eight plan clears the bar. Their document said it was essential for the GOP to participate in the immigration debate and to seek to expand the party’s appeal. If the Gang of Eight plan passes the Senate — understanding that the House may stop that momentum cold — the RNC reformers will, for however brief a moment, lay claim to having helped push the party in the right direction.

6. The impulse to excommunicate, as Peter Wehner calls it, would be interrupted if the Gang of Eight commands a healthy majority. Wehner writes on the increasingly ugly attacks on Rubio and other pro-immigration reform leaders:

Even if one disagrees with Rubio and Ryan on immigration, the attempt to portray them as traitors to the conservative cause is ludicrous. . . . Those who are drawn in the direction of purity or excommunication, who seem intent on elevating every difference into an apocalyptic battle over principle, are doing the work of liberals, which is to diminish the appeal of conservatism.

Marco Rubio and Paul Ryan may be right or they may be wrong on immigration reform. But they are among the most impressive and appealing conservatives in the land. If their stance on immigration reform leads some on the right to turn on them with a vengeance, it will be far more of an indictment of their critics than it will be an indictment of Rubio and Ryan.

But the larger the victory the less strength the excommunicators will have. At some point they take on a Monty Python-like quality — defeat for these forces is more than a scratch.

This is not yet a done deal by any means. And it is only one legislative battle — and one that may well stall out in the House. But passage of immigration reform even in the Senate would suggest the potential for a different sort of GOP than many have characterized of late — one willing to take risks and govern, one more in touch with voters and more dismissive of pundits and one with a new crop of leaders. That and the legislation that may flow from it could revive the party and contribute much to the country.

But first the Senate Republican’s need an amendment, a vote and passage of a bill.