The Senate Republican leader and House speaker intensified their push to secure spending cuts as part of any deal to increase the national debt limit -- a battle that had been widely expected to begin after the November elections, when the country will again need to raise the borrowing limit.
The U.S. debt is expected to hit its current limit of $16.4 trillion in January.
McConnell told CBS' "Face the Nation" now is "the perfect time" to talk about the debt because it points up before the November elections the nation's "excessive spending and borrowing, particularly over the last three and a half years."
When asked if he intended to have serious discussion about the debt now or at any time before the election, McConnell said nothing would be done until Obama formally requested a federal debt-ceiling increase.
"The timing will be determined by the president," he said, adding he assumed that would happen "at the end of the year or, early next year."
Concerning the blame for long-term U.S. debt, "we all know that it's on the entitlement side," McConnell said. "So at some point here, this president needs to become the adult because the speaker and I have been the adults in the room arguing that we ought to do something about the nation's most serious long-term problem."
Entitlements include Social Security, Medicare, Medicaid, most Veterans' Administration programs, federal employee and military retirement plans, unemployment compensation, food stamps and agricultural price-support programs.
McConnell and Boehner, an Ohio Republican, said on separate Sunday interview programs they considered sovereign debt to be the nation's biggest problem -- and Boehner likened the U.S. debt crisis to that of Greece.
"You know, people aren't clamoring to invest in Greece today," Boehner told ABC's "This Week." "And if we don't begin to deal with our debt and our deficit in an honest and serious way, we're not going to have many options.
"Listen, I'm not going to apologize for leading," he added. "The real issue here is, will the president lead?"
House Minority Leader Nancy Pelosi, D-Calif., told "This Week" Boehner was playing brinkmanship by advocating austere measures that don't allow for economic growth.
"The speaker wants to go over the edge," she said. "We have cut over a trillion dollars since the Budget Control Act of last year," which ended the last U.S. debt-ceiling crisis that threatened to push Washington into sovereign default on or about Aug. 3, 2011.
"There has to be more reductions, but we have to have revenue and we have to have growth," Pelosi said.
She said if Boehner were serious about moving quickly on economic matters, he should take action on middle-class tax cuts.
"I challenge the speaker right now to bring the middle-income tax cuts to the floor," she said.
"Passing those would help our economic recovery [and] would be a clear signal that the upper-end tax cuts for the wealthy will expire because the middle-income tax cuts will not be held hostage to those," she said.