That's Mitt Romney's new ad.
Meanwhile, Ryan Lizza has this big piece in The New Yorker about the Republican Party's embrace of "nativism." Excerpt:
“[Immigration] does appear to be the issue out here wherever we are,” [Mike Huckabee] told me. “Nobody’s asked about Iraq—doesn’t ever come up. The first question out of the box, everywhere I go—Iowa, New Hampshire, South Carolina, Florida, Texas, it doesn’t matter—is immigration. It’s just red hot, and I don’t fully understand it.”
Romney has not been similarly reflective in trying to discern the source of the issue’s power. Rather, he has quickly and easily adopted the negative code words of the anti-immigration movement—“sanctuary cities,” “amnesty”—and has tried to attach them to Giuliani and Huckabee. In doing so, he became the first top-tier candidate to seize the Tancredo mantle. My own sense, from talking to Huckabee, a Southern populist, and McCain, a border-state senator, is that they are genuinely appalled by Romney’s tactics, not only because of the damage to their campaigns but also because of the damage they believe he’s doing to the Party’s image....
[L]ast week, Huckabee, too, found his inner Tancredo: he announced the Secure America Plan, which included tough language about enforcement and pressuring illegal immigrants to return home. This leaves McCain as the only Republican candidate who hasn’t folded in the face of Romney’s attacks. At the press lunch in Virginia, after McCain had discussed his warm relations with several candidates, a reporter asked about Romney. “I’ve never known him,” McCain said icily. “I’ve never had a relationship with him.”