Last Wednesday, Mitt Romney hit Rudy Giuliani where it hurt the most. When Giuliani was mayor, Romney said in a speech in Bettendorf, Iowa, "he instructed city workers not to provide information to the federal government that would allow them to enforce the law.

"New York City was the poster child for sanctuary cities in the country."

Giuliani's campaign promptly rejected the charge. But that was last week. Today in stops across South Carolina, Giuliani will unveil, as his campaign announced, "his commitment to end illegal immigration" by enforcing immigration laws and controlling the borders with stepped up patrols and fencing, real and virtual. Giuliani further would create a tamper-proof entry card and "a single national database of non-citizens to track their status." And he would force immigrants to "truly read, write and speak English."

Clearly Giuliani's plan is forward-looking, since for now it makes scant mention of the 12 million or so illegals already here. If you can identify every non-citizen in the country, presumably you can identify every non-citizen who came illegally. Why not deport them once you've found them? Instead the mayor calls for deporting only those who commit a felony. You could call it his M&M policy: hard on the outside, soft in the middle.

Because as every New Yorker knows, and as The New Yorker's Peter Boyer put it in this week's issue, Giuliani has always been an "immigration softie." It is, in fact, true, as Boyer writes, that Giuliani instructed "city employees -- including cops -- not to cooperate with federal I.N.S. agents looking for illegal aliens." (Giuliani told Boyer that chasing after "cooks and gardeners" was a waste of resources, and that he feared immigrants facing deportation wouldn't cooperate with criminal investigations.") An article by David Saltonstall in today's New York Daily News highlights some of Giuliani's stances as mayor:

*He guaranteed immigrants access to schools, health care, and the police without regard to their status.

*"Some of the hardest-working and most productive people in this city are undocumented aliens," Giuliani said in 1994. "If you come here and you work hard and you happen to be in an undocumented status, you're one of the people who we want in this city."

*When nearby Suffolk County considered a bill to make English its official language in 1996, Giuliani denounced it. " "There's no reason to pass a bill like this, except maybe to exclude people, insult people or offend people," he said.

Here in New York, we're not ashamed of all this -- every mayor since at least Ed Koch in the 1980s (who told the Daily News that Giuliani "is repudiating the good things that he did, to his shame") to Bloomberg today has held similar positions.

But given Romney's own history, he should be the last person to give Giuliani grief over flip-flopping.