Number of grand coalition-opposed Social Democrats very small-finance minister

BERLIN, Nov 25 (Reuters) - Olaf Scholz, Germany's finance minister, said he was optimistic that his party's governing coalition with Chancellor Angela Merkel's conservatives will hold after a leadership vote.

"I am noticing that the number of those party members willing to exit the coalition without a good reason has become very small," Scholz, a member of the Social Democrats, told broadcaster Deutschlandfunk on Monday.

Scholz, who is the frontrunner to become the Social Democrats' co-chair next weekend, is being challenged by two candidates of the party's more left-leaning branch.

His rivals have expressed scepticism towards the coalition. The Social Democrats, despite assuring a stable governing majority in Berlin, have served for years as Chancellor Merkel's smaller coalition partner, diminishing the party's electoral base. (Reporting by Tassilo Hummel; Editing by Christoph Steitz)