MADISON, Wis. — Democratic candidate for governor Tony Evers and Republican Lt. Gov. Rebecca Kleefisch, both cancer survivors, clashed Friday over protections for people like them with pre-existing conditions.

Kleefisch is featured in a new television ad in which she says as long as she and Gov. Scott Walker are in office, people with pre-existing conditions will be guaranteed health insurance.

That protection is extended under former President Barack Obama's Affordable Care Act, which Walker has been working for years to repeal. He signed off on Attorney General Brad Schimel joining a multi-state lawsuit this year that seeks to undo the law and the pre-existing conditions protection.

But Walker this year also called for the Legislature to pass a state law guaranteeing coverage for the estimated 2.4 million people in Wisconsin with pre-existing conditions. The bill did not pass.

His campaign spokesman, Brian Reisinger, said Friday that Walker would call a special session of the Legislature "in a heartbeat" to pass the bill "if something were to change" and the federal guarantee went away.

Walker has no credibility on the issue because of his long opposition to the federal law, Evers said in a statement.

"Election year promises won't cover up Walker's career of working to sabotage Wisconsinites' health care and take us back to the days when insurance companies could deny you coverage if you got sick," Evers said. "He simply has no credibility on this issue, and Wisconsinites have no reason to believe he'd change with another term."

The Kleefisch ad follows one from a group aligned with the Democratic Governors Association that also featured a woman fighting cancer. In that spot, the woman claims that Walker doesn't care about families like hers because he's fought to repeal the health care law and its protections for people with pre-existing conditions.

In her ad, Kleefisch said she was "shocked" that Evers and his allies would argue Walker wants to end the protections.

"Today in Wisconsin, people with pre-existing conditions are already covered," Kleefisch said, without noting that is because of the national law Walker opposes. "And as long as Scott and I are in office, they always will be."

Evers, 66, is a survivor of esophageal cancer, which doctors told him he was cured of in 2012 after extensive surgery in 2008 requiring removal of his esophagus and part of his stomach. It's a cancer that few people survive and that Evers has said he thought would kill him.

Kleefisch, 43, was diagnosed with colon cancer at the age of 35 in 2010, during a five-way primary for lieutenant governor. She had surgery to remove the tumor and part of her colon and underwent chemotherapy treatments during the protests at the Capitol in 2011 over Walker's proposal known as Act 10 that effectively ended collective bargaining for most public workers.

This latest ad isn't the first Kleefisch has run featuring her cancer diagnosis. In a 2010 spot, during Walker's first run for office, Kleefisch falsely said the Democratic candidate Tom Barrett supported a government takeover of health care.