By Erik Kirschbaum
BERLIN (Reuters) - Chancellor Angela Merkel averted a potentially embarrassing defeat in parliament when rebel members of her centre-right coalition accepted a compromise plan on Monday to require German companies to put more women on their boards.
The threat of a rebellion had loomed just five months before Germany holds an election in which Merkel will be trying to win a third term. Leading conservatives, including Labour Minister Ursula von der Leyen, were threatening to break ranks and vote with opposition parties, convinced that voluntary pledges to appoint more women have proven inadequate.
CDU General Secretary Hermann Groehe said that under the compromise the CDU will include in its campaign platform a pledge obliging big firms to raise the proportion of women on supervisory boards to 30 percent in 2020.
In exchange for that pledge, coalition rebels agreed vote against the opposition's measure to introduce a quota from 2018. The Bundestag lower house is due to vote on the measure on Thursday.
Groehe, who had previously rejected any set quota, said von der Leyen had agreed to the compromise. But the minister did not make any public statement.
The opposition-backed measure would require Germany's 30 largest listed DAX companies to allot 20 percent of their board seats to women in 2018, with the quota rising to 40 percent in 2023.
It originated in the upper house of parliament, where the Social Democrats (SPD) and their Greens allies secured a majority earlier this year.
With the election looming and Merkel's party far ahead in the polls, the centre-left opposition is looking for ways to upset her campaign.
Besides to the women's quota, the left is planning to use its new majority in the Bundesrat to force votes on other issues that divide conservatives, including equal tax treatment for gay couples and subsidies for stay-at-home parents.
Merkel allies, led by parliamentary floor leader Volker Kauder, applied pressure on von der Leyen and other deputies who had spoken out in favour of the quota for women.
Von der Leyen, one of the few members of the CDU who has openly challenged Merkel on policy issues in recent years, has long supported the so-called "Frauenquote" but had kept mum about how she would vote on Thursday. She was seen as the pivotal voice and all eyes were upon her.
(Reporting By Erik Kirschbaum; Editing by Noah Barkin)