Members of the main Western-backed Syrian opposition group say they have postponed a vote on whether or not to attend a peace conference in Switzerland this month.

The Syrian National Coalition had been expected to decide Tuesday whether or not to attend the so-called Geneva peace conference, which is to open Jan. 22 in Montreux, Switzerland.

But coalition officials say that amid sharp disagreement over the issue, the vote was postponed until at least the middle of next week. That would be less than a week before the conference. The postponement of a vote whose outcome is uncertain adds to doubts about the conference whose prospects already look shaky.

Hadi Al Bahra, a member of the coalition's political committee, said the vote could happen as early as the Jan. 15.