UNITED NATIONS — Russia remained at loggerheads with the U.S. and its European allies ahead of a scheduled vote today on a new Syria resolution, and there appeared to be little hope that the U.N.’s most powerful body would unite behind a plan to end the 17-month civil war in the Mideastern country.

The key stumbling block is the Western demand for a resolution threatening non-military sanctions and tied to Chapter 7 of the United Nations Charter, which could eventually allow the use of force to end the conflict in Syria.

Russia is adamantly opposed to any mention of sanctions or Chapter 7. After Security Council consultations Tuesday on a revised draft resolution pushed by Moscow, Russia’s deputy U.N. ambassador, Alexander Pankin, said these remain “red lines.”

Russia has said it will veto any Chapter 7 resolution, but council diplomats said there is still a possibility of last-minute negotiations.

There has been a lot of diplomatic scrambling to try to get council unity, which would send a much stronger signal to Syria.

International envoy Kofi Annan has been in Russia for two days of high-level meetings, including talks with President Vladimir Putin Tuesday.

Annan said in Moscow that he and Putin focused on “what measures need to be taken to end the violence and the killing and how we move on to the political transition,” and he urged the council to try to find language “that will pull everybody together for us to move forward on this critical issue.”

The mandate of the 300-strong U.N. observer force in Syria expires Friday, and the Security Council must decide by then whether to extend it.

The U.S. and its European allies contend that the unarmed observers were authorized for 90 days to monitor a cease-fire and implementation of Annan’s six-point peace plan, and with violence dramatically escalating they insist that there must be consequences for non-compliance.

The Western draft would impose non-military sanctions against Assad’s regime if it fails to withdraw troops and heavy weapons from populated areas within 10 days, a key plank of the Annan plan.