The promise of bipartisan co-operation in Washington following the congressional mid-term elections came under immediate strain yesterday as the White House squared up to the Democrats over the US ambassador to the United Nations and a timetable for the phased withdrawal from Iraq.

Josh Bolten, the White House chief of staff, told ABC news that the administration would make a final attempt to have John Bolton, the ambassador to the UN, confirmed during the lame duck session of the outgoing Republican-dominated Congress, which begins today.