A heavy-hitting Republican group is going up on the air with a new ad, starring Marco Rubio, that makes the case for comprehensive immigration reform. The spot, which is set to air in six states, represents a major push to court conservatives who might be reluctant to accept the Gang of Eight Senate compromise.

The group — which is called Conservatives for a New Direction — is made up of a number of heavy-hitting elite Republican strategists. As Politico puts it, the big names illustrate “the fierce intensity of elite pressure on Republicans to pass a bill.”

The ad repeatedly describes the compromise bill as “conservative,” arguing that it “puts in place the toughest enforcement measures in the history of the United  States, potentially in the world, and it once and for all deals with the issue  of those that are here illegally.” It says: “stand with Marco Rubio to end de facto amnesty.”

It really is noteworthy just how hard Republicans are leaning in on immigration reform right now. Rubio’s office is running what amounts to a rapid response political operation designed to shoot down all the lies and distortions about reform coming from the right. And Republicans battling with conservatives have settled on their argument: It’s either immigration reform, or the “amnesty” status quo.

Consider what John Boehner and Paul Ryan had to say about the Boston bombings this week. While some on the right tried to use the bombings to slow reform, Boehner and Ryan took the opposite tack. Said Boehner: “If we fix our immigration system, it may actually help us understand who all is here, why they’re here and what legal status they have.” Added Ryan: “We have a broken immigration system, and if anything, what we see in Boston is that we have to fix and modernize our immigration system for lots of reasons.”

In other words, what the Boston bombings reveal is that reform is preferable to the unacceptable status quo, under which 11 million people are living in the shadows.

At this point, the worst possible outcome for Republicans when it comes to their efforts to repair relations with Latinos would be for the right wing of the party to sink this effort. And on this score, memories of 2007 must be vivid. Republican would-be reformers were caught off guard by the ferocious backlash that hit them from the right, an organizing coup that many believe was the reason reform collapsed last time. The push from Rubio and other GOP leaders — and from this new group of top GOP consultants — suggests a determination to avoid this fate again.

Remember, for a time pols like Rubio were taking a more cautious approach, carefully leaving themselves escape hatches for themselves in case the heat from the right got too intense, forcing them to bail on the. No longer. They’re all in. The effort isn’t just about reassuring and winning over conservatives. It’s about defeating those who can’t or won’t be won over. There’s now an unmistakable sense that there’s no going back.