The parliamentary spokesman for Greece's ruling SYRIZA party urged it on Wednesday to unite behind a new funding agreement, saying the country wanted a full bailout immediately rather than a bridge loan.
Nikos Filis said Greece was seeking a full agreement so that it could receive a first payment of 25 billion euros.
"We are seeking to have a deal," he said on state television station ERT. "The deal will have tough measures. What is important is that the financing of the Greek economy starts."
Filis was speaking amid signs of progress in talks between Greece, the International Monetary Fund and European Union institutions on a new bailout worth up to 86 billion euros ($94.5 billion).
A deal must be must be settled by August 20, or a second bridge loan agreed, if Greece is to pay off debt of 3.5 billion euros to the European Central Bank that matures on that day.
Both sides have said such a deal is possible, although the European Commission described the target as ambitious, suggesting a lot of work remains to be done.
Filis said Greece wanted the full deal, not a temporary measure.
"We will not accept new prior actions (reform conditions in place) in order to have a small bridge loan," Filis said. "We want one final deal to be signed and then we will see what is needed to have a disbursement of 25 billion euros as the first instalment."
He also called for members of his party, about a quarter of whom oppose the reforms and austerity linked to the bailout, to put the country first.
"Differences should not prevail over the party's unity and the country's stability," Filis said, warning that a split could damage the government.
"The leftist government will stay in power only if its leftist lawmakers vote in favor (of the bailout)."
Talks between Greece and its international creditors will continue on Wednesday.