The lack of agreement pushed the cost of insuring Greek debt against default to a new record high on Wednesday, while shares in Greek banks fell 7 percent on fears of political uncertainty.
The PASOK deputy who defected said he could not back the package. "You have to be as cruel as a tiger to vote for these measures. I am not," George Lianis said in a letter to Parliament Speaker Filippos Petsalnikos on Tuesday.
Another PASOK member said he would vote against it. But analysts said the party, which still holds a majority, would pass the package by the end of the month before working on another set of laws on how to implement it.
"My gut feeling is that at the end of the day they will get enough MPs... I'd say there is a 70 percent chance that it will go through," said Diego Iscaro, IHS Global Insight.
"The other option (voting it down) would be quite destabilising. That will drive MPs to vote for it."
The cabinet is also expected to survive the turmoil in the short term. A poll on Sunday showed 62 percent of Greeks expect the government to call early elections before its term ends in 2013, although 59 percent thought they did not need a vote now.