WASHINGTON — Senator Richard Burr, Republican of North Carolina, a reliable friend of business on Capitol Hill and no one’s idea of a bomb thrower, isn’t buying the apocalyptic warnings that a default on United States government debt would lead to a global economic cataclysm.

“We always have enough money to pay our debt service,” said Mr. Burr, who pointed to a stream of tax revenue flowing into the Treasury as he shrugged off fears of a cascading financial crisis. “You’ve had the federal government out of work for close to two weeks; that’s about $24 billion a month. Every month, you have enough saved in salaries alone that you’re covering three-fifths, four-fifths of the total debt service, about $35 billion a month. That’s manageable for some time.”

As President Obama steps up his declarations about the dire consequences of not raising the debt limit, increasing numbers of Congressional Republicans are disputing that forecast, as well as the timing of when the Treasury might run out of money and the implications of a default, further complicating the negotiating situation for both Mr. Obama and Speaker John A. Boehner, who must find a way out of the impasse.