Republican presidential candidates have been very vocal about the actions of American Muslims lately, and one of the latest White house hopefuls to explain what “most” Muslims are doing is Rick Santorum. The former Pennsylvania senator said Monday that the majority of Muslims in the U.S. are not working hard enough to address Islamic extremists.

Santorum’s comments came during an interview on MSNBC’s “Morning Joe” in response to a question from the hosts about his remarks at last week’s GOP debate that “all jihadists are Muslims.”

“There are Muslims in this country who are ... actually going out and trying to establish a reform Islam, trying to deal with the problem, the cancer within Islam. And it's real,” Santorum said Monday. “The bottom line is many Muslims are simply not doing that.”

The candidate, who has a national polling average of 0.5 percent, also criticized the country’s largest Muslim civil rights group, the Council on American-Islamic Relations (CAIR), saying it was not helping combat radical terrorists. “There are organizations like CAIR that are continuing to apologize for the radicals,” Santorum said.

His fellow Republican candidate Dr. Ben Carson made a similar claim about the organization last week, when he called for the State Department to investigate CAIR as a “supporter of terrorism,” an idea that has circulated in right-wing media and blogs for years. CAIR quickly denounced the terror attacks in Paris and San Bernardino, California, as it does with all terror incidents, and has been working overtime in recent months to address an uptick in attacks against American Muslims around the country.

CAIR and other Muslim groups have said the rise in anti-Muslim attacks is likely caused by backlash from recent terror attacks and by the anti-Muslim rhetoric that has become increasingly common among GOP politicians. Donald Trump, who has been the front-runner in the Republican race for months, drew intense criticism when he called for a temporary ban of all Muslims entering the U.S. earlier this month. Still, other politicians like Santorum continue to criticize the American Muslim community.

The “Morning Joe” hosts pushed back against Santorum’s comments on Monday, pointing out that the shooter who attacked a Planned Parenthood facility in Colorado this month was a white male who identified as “pro-life.” Mika Brzezinski, one of the hosts, asked Santorum why he was not calling on white men to denounce terrorism in the same way he was calling for Muslims to do so.

“There are lots of Muslims out there who are actually trying to confront the cancer. And the bottom line is, most are not, and that's a problem,” Santorum said Monday.