COLUMBIA — South Carolina's Latino population — and its share of illegal immigrants — has surged in recent years, and the anxiety has surged as well.

The number of Latinos in the state jumped 148 percent from 2000 to 2010, one of the largest increases in the nation. Gov. Nikki Haley pledged, as a candidate in 2010, to bring South Carolina an Arizona-style law cracking down on illegal immigration, and she signed one in June.

The anxiety was evident at Monday night's Republican presidential debate in Myrtle Beach, when a flurry of boos erupted after journalist Juan Williams mentioned that front-runner Mitt Romney's father was born in Mexico.

And yet it is Romney, with his hard-line stance on immigration, who finds himself particularly well positioned to tap that anxiety. The question now, as Romney seeks to separate himself from a crowded field in Saturday's South Carolina primary, is how far he is willing to go in doing so.

Romney has criticized Newt Gingrich — running second to Romney in most South Carolina polls — for proposing a path to legal status for some illegal immigrants; a Romney spokesman derided the plan as 'amnesty.'

Romney also has criticized Rick Perry for signing a law that granted in-state tuition to illegal immigrants.

At a Hilton Head town hall meeting Friday with Haley, Romney voiced support for crackdown laws like the ones in Arizona and South Carolina, portions of which have been blocked by federal judges after challenges from the Justice Department.

At Monday's debate, after the booing, Romney reiterated his opposition to the Dream Act, federal legislation that would offer young illegal immigrants attending college a path to legal status.

'I think we have to follow the law, and insist that those that have come here illegally ultimately return home, apply, get in line with everyone else,' Romney said.

Despite his victories in Iowa and New Hampshire, Romney remains dogged by criticism that he is not conservative enough for the modern-day GOP, and the immigration issue gives him an opportunity to attack rivals like Gingrich and Perry from the right.

But some observers say he must also be careful about coming across as too extreme on the issue, and potentially alienating moderates in the general election.

'They're trying to skate a very fine line right now,' said Joel Sawyer, a South Carolina Republican political consultant who had worked for Jon Huntsman's campaign. 'Romney has tacked to the right on (immigration), but not so hard that he's not going to be able to tack back to the middle if he gets to the general election.'

In the debate, Romney made a point of stating his 'love' for legal immigration, but illegal immigrant advocates argue that he has already crossed a line.

Their recent reaction to the candidate's message on the incendiary topic offers a glimpse of the rhetorical strategy they may employ against him if he becomes the nominee.

Last week, Romney touted his endorsement from Kris Kobach, the Kansas secretary of state and a key architect of the crackdown laws passed in Arizona, South Carolina and other states.

The pro-immigrant group America's Voice criticized Romney for associating with an 'anti-immigrant radical.'

Rep. Luis V. Gutierrez, D-Ill., who spoke in a conference call with reporters, called Kobach a 'dark lord' and said the move would hurt Romney among the nation's growing segment of Latino voters.

'There is no route to the White House that does not go through a Latino neighborhood,' Gutierrez said. 'Latino voters are not stupid, and we will have a very good memory of those who stood with us.'

The country's mood on immigration policy can be difficult to pin down. Recent nationwide polling has shown majority support for Arizona's strict law, but also majority support for a path to legal status for illegal immigrants.

Romney thus far has impressed Teela Roche, a computer support worker at Clemson University who heads the anti-illegal-immigration group South Carolinians for Immigration Moderation.

'He'll enforce the law,' said Roche, 58. 'He's said a lot of good things.'

A Washington newspaper reported that Kobach would appear in South Carolina with Romney on Monday — a report the Romney camp said was inaccurate.