Key Democrats say likely can't block Bolton

United States Senate Foreign Relations Committee Democrats think their party is unlikely to be able to block John Bolton's nomination as US ambassador to the United Nations.

The Senate returns this week from recess and again will face the contested nomination, which has twice been delayed by Democratic concerns about Bolton, the top US diplomat for arms control, who they say has a record of abusive, erratic behaviour that should disqualify him for the sensitive diplomatic job.

Asked if Democrats would have enough votes to sustain a filibuster, a procedural hurdle used to block the confirmation vote, Senator Joseph Biden of Delaware, the top Democrat on the panel, said, "I'm going to be completely straight with you. I'm not at all certain we do."