Washington ? The House of Representatives on Friday rejected setting congressional deadlines for withdrawing U.S. troops from Iraq in a vote that Republican leaders orchestrated to emphasize Democratic disunity over the 3-year-old war.

Forty-two Democrats voted with Republicans in the 256-153 final tally on a resolution that equated the conflict in Iraq with the war on terrorism and vowed to “complete the mission” in Iraq and to resist any “arbitrary date for withdrawal.” A majority of the Democrats who voted for the resolution were from conservative Southern congressional districts or swing districts that have voted Republican in the past.

The vote was the culmination of 11 hours of House debate about U.S. policy in Iraq, the most prolonged congressional debate on the war since American troops conquered Baghdad in the spring of 2003. It came less than five months before congressional elections, amid flagging public support for the war and as the number of U.S. soldiers killed in Iraq reached 2,500.

But the House also acted in the wake of positive news from Iraq for the Bush administration, including last week’s killing of Abu Musab al-Zarqawi, the leading al-Qaida figure in Iraq, and the completion of the Iraqi Cabinet after five months of bickering. Republicans returned to that theme time and again.

“The effort and savagery of the insurgents and their sponsors only underscores our progress and the importance of this effort in the global war on terror,” said House Republican leader John Boehner of Ohio. “Retreat is not an option in Iraq.”

Democratic leader Nancy Pelosi called the war a “grotesque mistake,” however.

“We’re halfway through 2006, significant transition has not occurred and the only redeployment has been of U.S. forces into Iraq, not out,” Pelosi said. “It must be our resolve to end the war as soon as possible.”

The House vote sets up a debate in the Senate next week, prompted by calls from Democratic senators to begin withdrawing troops this year. Liberal activists have pressed Democrats to set a timetable for troops to come home, a demand many Democratic lawmakers have resisted.

A proposal to withdraw troops by the end of this year failed Thursday in the Senate, 93-6.