Erskine Bowles, former co-chair of President Barack Obama's debt commission, indicated on CNBC that Thursday's deadline set by the Treasury to increase the debt ceiling may be flexible.
"My best bet is Thursday's a soft date," he said in a "Squawk Box" interview on Monday. "I think it would have real adverse effects in the [financial] market, if we don't go by Thursday."
There have been questions raised about exactly when the U.S. would default on its obligations, should the Thursday deadline to hike the nation's $16.7 trillion borrowing limit not be met.
One faction of the Republican Party has said there's no such deadline, because the U.S. has plenty of revenue to pay the interest on the federal debt. Rep. Mo Brooks, R-Ala., told "Squawk Box" as long as the interest is paid, there would be no U.S. default. Other government obligations, like Social Security, can go unpaid if necessary, he argued.
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"But here's the deal," countered Bowles, co-chair of the Fix the Debt group, which launched a new national advertising campaign Monday. "I would open the government. I'd pay our bills. And I'd set up a tight time frame to negotiate this deal." The government shutdown entered Day 14 on Monday.
"They're like children, except they don't have any good manners," he said. "We've made promises we can't deliver on. That's what we have to admit, whether it's on Medicare, Medicaid, Social Security."
Sen. Bob Corker, R-Tenn., also appearing on "Squawk Box," said he took issue with those comments. "Erskine is one of my heroes. I really enjoy working with him. But candidly, there are a lot of 'adults here' … who want to solve these problems."
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"There have been some movements in the wrong direction," Corker admitted. "We've ended up in this box canyon that candidly I predicted months ago."
Getting out of that canyon is going to take give-and-take on both sides, explained Bowles, who served as chief of staff for President Bill Clinton. "I walk through every single airport and people yell at me, 'For God-sakes stop the madness in Washington. Get these people talking. Solve the problem.' They want real action."
(Watch: Erskine Bowles asked to to 'stop the madness')
"They want these guys to get in a room and start negotiating" like the Clinton administration did in 1996 with then-House Speaker Newt Gingrich, Bowles said. "We got the government back open again [then] and we were able to balance the budget. Both of us made compromises."
He said intractable partisanship is not an excuse. "We did it when [Republicans] were trying to impeach Clinton. It was pretty partisan back then, I felt. But I spent months and months locked in conference rooms … and we worked it out. That's what we need to do now."
"Hopefully we can get a timeline set up and an agreement that people will get into a room and talk about just three of four things," he said, "reforming the tax code … reforming these entitlement programs … making Social Security sustainably solvent" and replacing the across-the-board, mandatory sequester spending cuts.
—By CNBC's Matthew J. Belvedere. Follow him on Twitter @Matt_SquawkCNBC.