Mitt Romney, conveniently forgetting that when he was governor of Massachusetts some of its cities were "sanctuary" cities, has taken lately to criticizing Rudy Giuliani for having been supportive of illegal immigration while he was mayor of New York.

Giuliani has now responded with his own notion of how he would deal with the illegal alien problem:

AIKEN, S.C. (AP) - Republican presidential hopeful Rudy Giuliani vowed Tuesday to stop the flow of illegal immigrants into the United States by closely tracking visitors to the country and beefing up border security.

"We can end illegal immigration. I promise you, we can end illegal immigration," the former New York mayor said at a community center - the first of the day's two stops in this early voting state.

Giuliani said he would require a uniform identification card for foreign workers and students and create a central database to track the legal status of visitors to the country. He told the crowd of more than 300 that 12 million immigrants have entered the country illegally.

"That's a lot of people to walk over your border without being identified," he said.

Giuliani wants a tamperproof ID card that includes fingerprinting for everyone entering the country and a central database to track when they leave.

The ID card and other immigration proposals have been part of Giuliani's campaign speeches for several months. He says he would allow a pathway to citizenship only for illegal immigrants who identify themselves as illegal, who learn English and who go to the back of the line to apply.

In recent days, rival Mitt Romney, the former Massachusetts governor whose state has been home to a few self-proclaimed "sanctuary cities," such as Cambridge, Mass., has repeatedly criticized Giuliani, arguing that he supported illegal immigration when he was mayor. Giuliani rejected the charge.

Gov. Romney may want to get his story about why he changed from pro-choice to pro-life so quickly a bit more straight before he takes Mayor Giuliani to task on illegal alien and security matters. But if Romney wants to fight, it looks like Giuliani is more than willing to engage and return the fire.