Angela Merkel has been desperately trying to form a coalition since her disaster at the ballot box last September.
After talks on a three-party deal collapsed, she is trying to reform her previous coalition with the Social Democrats (SPD) with a vote expected on an agreement on Sunday.
But Wolfgang Schäuble, who gave up his finance portfolio to become president of the Bundestag lower house after an election last year, said today even if the talks failed it would not be a disaster.
He said: “If it doesn’t work, it is also no catastrophe.
“There are other ways it could work.”
And, in a rare jab at Mrs Merkel, Mr Schäuble said Germany was still “suffering” from the Chancellor’s decision in 2015 to leave open the country’s borders, allowing in over a million people seeking asylum.
That crisis was widely cited as a reason for Mrs Merkel’s election drubbing and a surge in the far-right vote.
He said: ”We are still suffering as a result. I don’t want to trivialise it.”
Delegates from the left-leaning Social Democrats vote this Sunday on whether or not their leaders should push ahead with the coalition.
Mrs Merkel’s CDU and the party reached a preliminary deal last week after slow-moving talks.
But the result of this weekend’s vote is far from clear, despite an appeal from SPD leader Martin Schulz for party members to back a re-run of their grand coalition that has governed Germany for the past four years.
The SPD’s share of the vote in last September’s election dropped to its lowest level since Germany became a federal republic in 1949, and many members fear another four years in coalition with the Chancellor will further erode their support base.
A coalition blueprint agreed between the conservatives and the SPD last week left many in the centre-left party feeling the leadership had not pushed through enough of their own agenda.
Some also worry about the far-right Alternative for Germany gaining influence as the largest opposition party if there is a grand coalition.
A failure to stitch-up the alliance could lead to fresh elections, leaving Mrs Merkel with a mountain to climb among impatient voters disillusioned with her fruitless talks.