President George W. Bush on Wednesday entered a fresh round of negotiations with Democratic leaders of ­Congress over funding for the Iraq conflict, amid the most serious showdown between the White House and Congress over war policy since the Vietnam era.

Congressional leaders from both parties met Mr Bush at the White House on Wednesday, less than 24 hours after he vetoed a war-funding bill that included a timetable for withdrawal from Iraq. House Democrats attempted to overturn the veto but fell far short of the two-thirds majority required.