The Republican-controlled Senate on Thursday rejected Democratic calls to start withdrawing US troops from Iraq by year's end, as the two parties sought to define their election-year positions on a war that has grown increasingly unpopular. "Withdrawal is not an option. Surrender is not a solution," declared Senate Majority Leader Bill Frist of Tennessee, who characterized Democrats as defeatists wanting to abandon Iraq before the mission is complete. In an 86-13 vote, the Senate turned back a proposal from some Democrats that would require the administration to withdraw all combat troops from Iraq by July 1, 2007, with redeployments beginning this year. Minutes later, the Senate rejected by 60-39 the proposal more popular with Democrats, a non-binding resolution that would call for the administration to begin withdrawing troops, but with no timetable for the war's end.