The South Carolina Republican said on the Senate floor he has "no confidence the president actually wants to make health care affordable and available to all Americans," noting that Obama voted against a number of Republican measures last year -- including pooling of insurance by small businesses and health savings accounts -- that DeMint said would have lowered health care costs.
The latest attack came as a key House committee on Tuesday indefinitely delayed voting on its version of the Democrats' health care reform legislation after Democratic leaders were unable to line up enough votes from moderate members of their own party.
In recent days, DeMint has declared that if Republicans defeat Obama's health reform efforts, it will be Obama's "Waterloo" -- and that it will "break" the president.
Obama seized on the comments Monday to suggest that politics are trumping the interests of the American people.
"This isn't about me. This isn't about politics," Obama said. "This is about a health care system that is breaking America's families, breaking America's businesses and breaking America's economy. And we can't afford the politics of delay and defeat when it comes to health care -- not this time, not now."
On Tuesday, DeMint stepped up his war of words with the president.
"Folks, as I look at this whole health care debate, I'm glad to see the president out attacking me for saying we need to stop him," he said. "It's time to slow down and take stock of where we are.
"Let's stop this rampage toward bigger and bigger government," he said. "Let's stop and get it right. Our health depends on it."
Senate Majority Leader Harry Reid, D-Nev., jumped into the fray Tuesday, mockingly calling statements like DeMint's "brilliant."
"Republicans aren't interested in working with Democrats to fix this problem," he said. "That's pretty clear. They simply want to maintain the status quo and keep the insurance industry in charge of health care delivery."
Meanwhile, Senate Minority Leader Mitch McConnell, R-Ky., took exception with reports that Republicans are merely trying to defeat health care reform efforts.
"I hear it said repeatedly by some on the other side that Republicans are not in favor of health care reform," he told reporters. "I can't find a single Republican senator who said that, nor whose speeches have not illustrated and underscored that we need to have health care reform.
"We do start with the notion, however, that we have the best health care in the world," he said. "Surveys indicate that ... the American people, when it comes to quality, believe that they have the best health care in the world. We know we have a cost problem, and we know we have an access problem."
FOX News' Trish Turner contributed to this report.