German Finance Minister Wolfgang Schaeuble has warned his country’s MPs that it would be “irresponsible” to oppose a third bailout deal for Greece.
He told a debate in parliament they should “seize the chance” for a new beginning for Greece.
MPs are to vote on the deal later. Chancellor Angela Merkel is expected to win approval but is bracing for a rebellion in her centre-right alliance.
The coalition is divided over the €86bn ($95bn; £61bn) package.
Between 60 and 100 coalition MPs could oppose the vote, commentators say.
Mrs Merkel’s coalition of Christian Democrats (CDU) and their Bavarian CSU allies holds 504 seats in the 631-seat Bundestag – enough to withstand the rebellion – particularly as the Social Democrats (SPD) and Greens want the bailout to go ahead.
However, the rebellion could weaken Ms Merkel’s authority nationally.
Last month, 65 CDU/CSU politicians refused to support even starting negotiations for a third bailout.
Mr Schaeuble was first to speak on Wednesday, urging the Bundestag to vote for the deal, saying the most important thing was to encourage growth in the Greek economy so that it could stand on its own again.
He said: “There is no guarantee that all of this will work and there can always be doubts. But considering the fact that the Greek parliament already approved most of the measures, it would be irresponsible not to seize this chance for a new beginning in Greece.”
The BBC’s Jenny Hill in Berlin says MPs are worried about two unanswered questions – the extent of any debt write-off for Greece and whether the International Monetary Fund will back the bailout.
The IMF is avoiding any commitment until Greece’s progress is assessed in October.
Some German MPs suspect that the deal could lead to part of Greece’s large debt being written off – with EU taxpayers having to foot the bill.
Conservative MP Dagmar Woehrl vowed to vote against the package, saying: “If we’re honest, this is a hidden debt haircut (write-down) at the expense of our children and grandchildren.”
But CDU General Secretary Peter Tauber warned a vote against the deal was “tantamount to stabbing the chancellor in the back”.
A number of parliaments in the eurozone, including Germany, are required to approve the deal with a vote. German MPs had to be recalled from their summer break.
On Tuesday, MPs in Austria, Estonia and Spain backed the bailout.
The Dutch parliament votes on Wednesday.
But doubts remain about the Greek government’s commitment to the bailout conditions because it previously pledged to oppose austerity.
Many MPs of the ruling Syriza party believe Prime Minister Alexis Tsipras allowed the eurozone lenders to dictate unacceptable terms to Greece, violating the country’s sovereignty.
In exchange for the bailout – and keeping Greece in the euro – Mr Tsipras agreed to further painful state sector cuts, including far-reaching pension reforms.
The new loans will be spread over the next three years. The first tranche will be €26bn – €10bn to recapitalise Greek banks and €16bn in several instalments, the first of which – €13bn – will be made by 20 August, when Greece must repay about €3.2bn to the European Central Bank (ECB).