The story

Republican presidential candidate Mitt Romney Tuesday stepped up his ongoing attack on cities with what he calls sanctuary policies for illegal immigrants -- including rival Rudy Giuliani's home city -- with a new radio ad set to air in crucial campaign states Iowa and New Hampshire.

"Immigration laws don't work if they're ignored," the ad's announcer states. "That's the problem with cities like Newark, San Francisco and New York City that adopt sanctuary policies. Sanctuary cities become magnets that encourage illegal immigration and undermine secure borders."

"Legal immigration is great," Romney, a former governor of Massachusetts, himself says in the ad. "But illegal immigration, that we've got to end. And amnesty is not the way to do it." Read full article »

CNN's Mark Preston contributed to this report.

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