Treasury Secretary Tim Geithner suggested Sunday that Republicans and Democrats alike have assured the president they will vote to raise the debt limit, even as some lawmakers threaten to leverage the looming vote to extract spending cuts.

Geithner, speaking on NBC's "Meet the Press," said "responsible" lawmakers understand how "catastrophic" it would be to balk on that vote. The United States government could hit its $14.3 trillion debt ceiling as early as next month.

"Congress is going to have to raise the debt limit. They understand that," Geithner said. "The leadership understand that you can't play around with this."

He said congressional leaders expressed that point in a meeting with President Obama last week. He said the administration wants to figure out a long-term deficit reduction plan while Congress takes up the debate over the debt limit, but that if the government hits that ceiling before a deal is reached, the ceiling will have to be raised regardless.

"Congress will raise the debt ceiling," he said, in a separate interview on ABC's "This Week."

Geithner said repeatedly that lawmakers who want to take the country to the "brink" will bear the responsibility for the risk that creates.

He suggested that merely flirting with that edge would create a problem. But he said if Congress ultimately rejects an increase in the debt limit, it would trigger a crisis that makes that 2008 meltdown look tame. Geithner reiterated warnings that such a vote would force the government to halt benefits payments to seniors and veterans and would risk the government defaulting on its interest.

Though Geithner said he's confident Congress will vote "yes" on the increase, a number of lawmakers continue to threaten to withhold their vote if they don't see progress on a deficit-reduction deal.

Sen. Tom Coburn, R-Okla,, said on "Fox News Sunday" that he needs to have "absolute certainty" a deficit reduction plan includes "critical changes."

"Unless we do that, there's no way I'll support it," Coburn said on the debt ceiling increase. "We're going to have a debt crisis, either with this or soon thereafter, if we don't come together."

Rep. Paul Ryan, R-Wis., the author of the Republicans' 2012 budget proposal, also said on CBS' "Face the Nation" that Congress won't "just simply raise the debt limit" without attached spending cuts.

Rep. Chris Van Hollen, D-Md., though, said Congress should not "monkey around with the full faith and credit of the United States."

"Linking the two and saying you're only going to vote for the debt ceiling if something particular happens on deficit reduction I think is playing Russian roulette with, like, the fully loaded revolver," he said on "Fox News Sunday."