In a web ad released Friday, former Massachusetts governor Mitt Romney goes after Texas governor Rick Perry on his perceived soft spot with conservatives: immigration.

But he does it in an interesting way. The web ad ties the governor, who supports in-state tuition rates for undocumented student immigrants, to Barack Obama, Nancy Pelosi, Harry Reid ... and Vicente Fox, the former president of Mexico.

Fox, who governed Mexico from 2000 to 2006, is not a particularly controversial figure in the United States, anyway. Depicting him as a bogeyman could damage Romney with Hispanic voters in the general election, should he win the Republican presidential primary.

The ad says that Romney is supported by Democratic leaders on tuition benefits, and then shows a clip of Fox thanking Perry and the state of Texas for supporting the policy. It ends with Perry and Romney sparring over the issue at the Sept. 22nd Fox News/Google debate.

Fox is the highlight of the Romney ad. He’s the only one of the four given a speaking role. It’s his “thank you” to Perry that gives the spot its name.

“It’s a false and outrageous attack from a serially inconsistent candidate,” said Perry campaign spokesman Ray Sullivan.

Fox was a centrist businessman elected after decades of socialist rule in Mexico. While he disagreed with then-President George W. Bush on the construction of a border fence and wished there had been more action from the White House on Latin American relations, the two leaders got along pretty well.

On MSNBC Friday morning, Chuck Todd asked Romney strategist Russ Schriefer whether his candidate didn’t risk offending Hispanics by playing the immigration card with this web ad.

“I think that legal immigrants — people who are here legally, who are first generation and second generation immigrants — are as offended as anyone else that they are subsidizing people who are here illegally, and I think that that’s not going to be a problem at all,” Schriefer replied.

Romney spokeswoman Andrea Saul added in a statement that it’s a problem for everyone that in-state tuition is one of “the magnets that encourage people to cross the border illegally.”

Yet polling finds that Romney strategists aren’t on solid ground on this issue. While opinion on many immigration issues is divided, polling shows that Hispanics across the board support in-state tuition for undocumented immigrant students.

According to a recent Pew poll, 77 percent of native-born Hispanics and 78 percent of foreign-born Hispanics support in-state tuition. Among the foreign-born, 83 percent of U.S. citizens and 77 percent of legal residents back the idea — more than the 71 percent of Hipsanics without legal residency.

With President Obama’s approval rating among Hispanic voters in key states sinking, Republicans think the right candidate could win over some of those voters. But demonizing immigrants and Mexican politicians could make that more difficult.

“Florida, Nevada, New Mexico — the Democratic party can take this ad and re-use it against Mitt Romney in a lot of these battleground states,” said Hector Barajas, a California Republican strategist.

On the other hand, a 2007 L.A. Times poll found that only 12 percent of Americans want to give in-state tuition to undocumented immigrants. Among Republicans, that number was only six percent. Perry has been on the defensive on this issue, having walked back a comment in last week’s debate that those who opposed his policy “don’t have a heart.”

Rep. Michele Bachmann (R-Minn.) had a hard-hitting ad on the same issueout on Friday. But Romney’s attack is less subtle, and if he succeeds in the GOP primary it may come back to haunt him in the general election.