Few issues have more power to expose a politician’s true colors than immigration.

Take Marco Rubio. Conservative, smart, articulate, and unflappable, all wrapped in an ethnicity that would confound the Left’s racist-Republican narrative. It wasn’t very long ago that most of the Right agreed he’d make an ideal standard-bearer. Personally, I was disappointed that Mitt Romney passed over Rubio for Paul Ryan as running mate.

What a difference a few months make. Solely by embracing the latest “comprehensive immigration reform” push, Rubio has cast insurmountable doubts on his own conservatism, trustworthiness, and competence.

That last one may be both the most surprising and the least noticed. According to Politico, Rubio’s advisers fret that sticking his neck out for the Gang of 8 plan has earned him the dreaded “Washington insider” label. What did they think was going to happen? Regularizing illegal immigrants has always been a fixation of political elites, not middle America. The common man’s interests in the issue are securing the border and keeping illegals from taking Americans’ jobs, leeching off government programs, and being around to commit crimes.

For Team Rubio to take up an insider cause without being prepared to accept that it makes them insiders displays a shocking political ineptness. His advisors either have no feel for the values and desires of their constituents and how they differ from Washington’s—which is presumably a big reason why Rubio pays them in the first place—or they arrogantly expect to tell the little people what they should want. And apparently, Rubio himself doesn’t think differently enough to recognize when they’re feeding him bull. Add in the staffer who told the New Yorker we need a guest worker program because of all the American workers who “can’t cut it,” and Rubio’s personnel choices don’t exactly inspire confidence in his leadership abilities.

As for trustworthiness, Rubio’s constantly shifting assertions about the bill put John Kerry to shame. National Review’s editors summarize:

“He is refusing to say whether he will vote ‘yes’ on his own Gang of Eight bill after spending months drafting, defending, and helping shepherd it to the floor. He has supposedly discovered that the enforcement provisions are inadequate, although he has done countless interviews touting that the bill contains the “toughest immigration-enforcement measures in the history of United States” (which is what his website still says). At the same time, Rubio declares the bill 95–96 percent perfect.”

In the Gang of 8 bill, Janet Napolitano can issue waivers for criminal records and failure to pay back taxes. The border-fence mandate is riddled with loopholes. Illegals only need to sign up for an English class, not attain proficiency in the language. The only consequences for failing to meet the bill’s definition of a secure border are non-binding recommendations from a commission. Just like ObamaCare, we discover a whole new set of failings every week. If Rubio’s constant promises that he’d abandon the bill if it failed the security test were ever sincere, he would have done so long ago.

It’s not just the defects Rubio’s trying to smooth over; his core objective varies depending on which audience he’s speaking to. He gushes about the importance of enforcement when talking to conservatives, but reassures Univision that “first comes the legalization,” which is “not conditional” on security results. And his insistence that illegals’ newfound citizenship will be “earned” is a complete reversal from his stance as a Senate candidate. During the October 24, 2010 debate with Charlie Crist, Rubio argued:

“First of all, earned path to citizenship is basically code for amnesty. It’s what they call it. And the reality of it is this. This has to do with the bottom line that America cannot be the only country in the world that does not enforce its immigration laws. It is unfair to the people that have legally entered this country to create an alternative pathway for individuals who entered illegally and knowingly did so. And all I’m saying is that if you do that […] you will never have a legal immigration system that works. No one is going to follow the law if there is an easier way to do it.”

(Ironically, a few minutes later he chastised Crist for “chang[ing] positions on the issues because he wants to win the election.”)

It’s bad enough to abandon conservative stances, but for Rubio to embrace something he once called not only wrong, but deceptive, is much worse.

Make no mistake: this bill is a scam to import a massive, permanent underclass, hook them on government services, then give them the vote—artificially inflating the Democrat base to a permanent supermajority. If that happens, the conservative movement is finished, and so is America.

Conservative leaders still clinging to unfounded hope that Rubio is merely naïve and well-intentioned—and that includes Rush Limbaugh, Sean Hannity, and Mark Levin—need to take off the kid gloves and make it clear to him that his treachery has discredited him as an ally to the movement, and that they will mobilize their audiences against him. Lt. Col. Allen West has expressed interest in challenging Rubio for his seat, and he needs sustained, high-profile encouragement now to do so.

(Rubio’s the biggest threat, but not the only one—Tea Party favorites such as Jan Brewer, Paul Ryan, and Kelly Ayotte who side with the Gang of 8 also need to hear that their standing is equally suspect. And while Rand Paul should be commended for opposing the final bill, he still needs to take heat for endorsing the concept of a path to citizenship.)

Amnesty might never have gotten this far if we had been keeping our superstars on a much tighter leash. Now our only hope is a hard, unified course correction, and a commitment to dole out accolades much more sparingly for future rising stars.