Mayor Giuliani’s attempt to recast himself as a strong opponent of illegal immigration is being met with skepticism from those on both sides of the immigration debate.

Mr. Giuliani gave a speech in the early primary state of South Carolina yesterday that seemed to respond to criticism from his one of his Republican rivals, Mitt Romney, who has generated headlines in the last week for painting Mr. Giuliani as lax on illegal immigration. But the former mayor, who had a reputation for his pro-immigrant policies in New York, does not seem to be winning over advocates for stronger immigration regulations or for those who think more visas are needed.

“It sounds like an effort by Giuliani to make himself seem like a hawk on immigration when, in fact, he’s been a dove all along,” the executive director of the Center for Immigration Studies, Mark Krikorian, said.

Mr. Krikorian favors a stronger crackdown on illegal immigrants. Mr. Giuliani told an audience of more than 300 people at a community center yesterday that he would secure the country’s borders and “end illegal immigration.”

“We can end illegal immigration. I promise you we can end illegal immigration,” Mr. Giuliani said, according to the Associated Press. The Republican presidential front-runner said those who are in the country illegally should be able to apply for citizenship if they identify themselves and then learn English.

He is also pushing the creation of a “national database of foreigners” and a “tamper-proof” biometric identification card for any non-American who is working or going to school in this country. He is also vowing to deploy 20,000 border patrol agents to deport illegal immigrants who commit a felony and to build a fence along the American border.

His focus on immigration comes less than a week after Mr. Romney criticized him for running a “sanctuary city” in New York when he was mayor. Mr. Giuliani defended his record, saying that when he was in office, New York had the lowest number of per capita illegal immigrants of any major city.

During a radio interview yesterday, the mayor said the country should focus its deportation efforts on those who commit crimes first. When talking about border patrol he said it was complicated but that it wasn’t “brain surgery.” Mr. Giuliani is no doubt caught in a difficult political position on an issue that has divided Republicans. Senator McCain, one of his other leading rivals, has taken more heat from conservatives on immigration than any other candidate in the field.

Mr. Giuliani must figure out how to square his reputation as a pro-immigrant mayor while appealing to conservative primary voters. Political analysts say he also needs to be wary of flip-flopping — something for which he and others have criticized Mr. Romney. A senior scholar at the Manhattan Institute, Tamar Jacoby, said Mr. Giuliani’s proposal is a “fairly responsible” first step but that it is too focused on enforcement.

“Trying to end illegal immigration with enforcement alone is like trying to maintain a zero-calorie diet,” she said. “It doesn’t work.” She said the country needs more visas for both unskilled and skilled workers.

Earlier this week, Mr. Giuliani appointed seven immigration advisers and sent out a memo detailing some of the harder-line comments he made on illegal immigration in the early 1980s.

The director of the Manhattan-based Center for an Urban Future, Jonathan Bowles, said Mr. Giuliani seems to have forgotten the “positive impact that immigrants, both legal and illegal, have had on New York and other cities.”

He pointed out that Mr. Giuliani created the mayor’s office of immigrant affairs when he was in City Hall and filed suit against the federal government for attempting to allow city employees to turn in illegal immigrants who came forward for city services.

A spokeswoman for Mr. Giuliani, Maria Comella, said the mayor has always been in favor of legal immigration but has also argued that the federal government has failed to secure the borders. “It’s a question of tackling this issue of the border security so that ultimately legal immigration can continue to grow,” she said.