WASHINGTON (CNN) -- Republican presidential hopeful Mitt Romney is attacking Mike Huckabee on his record of illegal immigration in a new TV ad, a move the latter labeled as "desperate."

Former Massachusetts Gov. Mitt Romney is upping the attacks on Mike Huckabee's immigration record.

Romney, who has lost his front-runner status in polls to Huckabee in Iowa, plans to air the ad on the issue he views as one of his rival's biggest vulnerabilities.

Iowa stations will begin broadcasting the spot, which attacks Huckabee by name, on Tuesday.

The Romney ad, titled "The Record," compares the candidates' conservative stands on social issues but draws a sharp contrast on their track records on immigration policy: "Mitt Romney stood up and vetoed in-state tuition for illegal aliens ... opposed driver's licenses for illegals," the ad's announcer says. "Mike Huckabee? Supported in-state tuition benefits for illegal immigrants. Huckabee even supported taxpayer-funded scholarships for illegal aliens. Watch the Romney ad »

"On immigration, the choice matters," the announcer says.

Romney spokesman Kevin Madden said the ad was intended to highlight the difference between the ex-Massachusetts governor's "pro-enforcement record" and Huckabee's stance on immigration in the past.

During an event Tuesday in Council Bluffs, Iowa, Huckabee called the ad "desperate" and said he thought it would backfire.

"I'm somewhat flattered in that I seem to be the recipient of the first negative attack ad in the Republican primary," Huckabee said. "That's usually the kind of desperation on the part of an opponent who feels that his only way of winning is to attack and destroy."

He added, "They see how much money they've spent, and we're winning. That causes people to do some sometimes desperate things."

Huckabee defended his decision to allow children of illegal immigrants to pay in-state tuition while he was Arkansas governor.

"I was dealing with the failure of the federal government at a state level, just like a lot of citizens have dealt with it individually, and my feeling was, and I still believe this, that you don't punish a child for the crimes a parent commits," Huckabee said. "And that's my position; it hasn't changed."

Huckabee is not allowing the portrayal of him as soft on illegal immigration to go unchallenged. He has received the endorsement of Jim Gilchrest of the Minuteman Project, a group that has called for tighter border security and a crackdown on illegal immigration.

"For months I've been searching for ... an actual plan," Gilchrest said. "And I found the Secure America plan put together by Mike Huckabee to fit right in with what I feel would help at least begin to solve this problem."

Romney has taken a tough stance on illegal immigration during the campaign, saying he would strengthen border security and implement a system that would allow employers to verify whether a person can work legally in the U.S.

During last month's CNN/YouTube debate, Romney also criticized Rudy Giuliani for allowing New York to become a "sanctuary city" for illegal immigrants while he was mayor, an allegation the rival candidate has denied.

But Romney's credibility on the issue came under question when The Boston Globe reported last week that a landscaping company Romney employed to take care of his Boston home continued to use illegal workers after the newspaper had reported a similar incident almost a year ago.

Romney fired the landscaping company last week, saying in a statement that "the company's failure to comply with the law is disappointing and inexcusable."

A senior Romney aide said that Romney's son Tagg had been personally assured by the company's owner, a family friend, that the firm wouldn't use illegal workers after the first report.

During the CNN/YouTube debate, Giuliani attacked Romney for living in a "sanctuary mansion," where illegal immigrants were allowed to work. E-mail to a friend

CNN's Dana Bash and John King contributed to this report.

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