ISTANBUL — Turkey rejected a US call to discontinue efforts with Russia and Iran to end the war in Syria and called on its Western allies to instead support the process as the region’s best chance at quelling the violence.

The debate over the so-called Astana peace process, named for the Kazakh capital where leaders from Russia, Iran and Turkey first met to tackle the imbroglio, comes ahead of a visit to Ankara by James Jeffrey, Washington’s special envoy on Syria, to discuss a slate of US-Turkish divisions over Syria.

On Monday, Jeffrey called the Astana process “rather strange” and a “stalemate” for its failure to make progress on a establishing a constitutional committee for Syria. “The US view is, ‘Let's pull the plug on Astana,’” he said at a briefing in Washington.

But Turkey has embraced the initiative, especially since its Western allies have all stepped back from a robust peace effort for Syria. Ankara enjoys warm ties with Moscow and Tehran, despite their backing of President Bashar al-Assad, while Turkey is the main supporter of opposition fighters who have sought to topple him.