Reports indicate that the prime minister could call a confidence vote, which may trigger fresh elections and jeopardize the bailout.
The Greek Finance Minister says there are "two or three very small details" remaining after all-night negotiations.
The bill lawmakers will vote on late on Wednesday covers rules for dealing with failed banks and speeding up the justice system.
Prime Minister Alexis Tsipras spent the day with his cabinet drafting a last-ditch package of tax rises, pension reforms and economic liberalization measures.
EU leaders will hold a further summit on Sunday to approve a plan to aid Greece if creditor institutions are satisfied.
The Eurogroup of euro zone finance ministers will hold a conference call early on Wednesday.
Getting the Greeks to say no was the easy part. Now Tsipras must quickly mend fences with his European partners.
Latvia, Ireland, Spain, Portugal and Slovakia endured austerity and are in no mood to allow Greece off the hook.
Tsipras said negotiations would continue for a better deal with international creditors after the vote.
The poll put the 'Yes' camp on 44.8 percent against 43.4 percent for the 'No' vote.
Greek prime minister shakes up negotiating team and takes controversial finance minister, Yanis Varoufakis, out of the limelight.
Experts say that the last minute clamp down is too little too late.
Angela Merkel says Grexit must be prevented while Varoufakis writes that disagreements with creditors are "not unbridgeable".
The environment minister has revoked a license leaving gold stuck in a mine in northern Greece.
Possibility of exit from euro zone has pushed up Greek bond yields but has had little effect globally.
Eurogroup says Athens's reforms are too optimistic, urges Greece to tackle issues of pensions and labour markets.
It was unclear if Greek Prime Minister Alexis Tsipras and German Chancellor Angela Merkel had narrowed differences on economic reforms for Greece.
Athens pledged not to roll back any reforms that could have a negative fiscal impact and to honor all its debts.