With euro zone leaders planning an emergency Greek debt summit on Monday, the chances of a reform-for-aid deal is probably 60 percent, former U.S. Deputy Treasury Secretary Roger Altman said Friday.
"I think the odds have narrowed," Altman told CNBC's "Squawk Box" following the failure of the region's finance ministers to reach an agreement this week. "But I still think the likelihood of a solution is greater than a blowup."
Greece has said that without further aid, it would be unable to make a $1.7 billion debt payment to the International Monetary Fund on June 30.
On Thursday, IMF chief Christine Lagarde raised the stakes—telling Athens there would be no grace period.
But Altman, a former Clinton administration official and Evercore Partners founder, remained skeptical. "These deadlines tend to be squishy," he said. "When push comes to shove, such deadlines often get extended."
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"Neither side has wanted to blink before it became absolutely completely, necessary to do so. I'm not sure either side thinks we're at that point yet," Pantheon Macroeconomics Chief Economist Ian Shepherdson told CNBC.
"The only good option for Greece is serious, large scale debt relief," said Shepherdson. "That's not going to happen in the short run." He said the financial markets are pricing in a kick-the-can-down-the-road deal.
Whatever the outcome of Greece, which makes up a small part of the euro zone's gross domestic product, there won't be a widespread financial impact, Altman said. "I don't think there's much contagion risk from a foreign exchange point of view [or] from a global bond market point of view."
Meanwhile, the European Central Bank on Friday raised the emergency fund cap for Greek banks, after expressing concern about whether banks there would open Monday. There have been withdrawals of about $2.2 billion in the past three days—a billion alone Thursday.
"I don't understand why anybody has money in Greek banks anymore. I'm surprised there was a billion dollars left to take out," Shepherdson said.