A man walks during an anti-war march in Portland on March 15, 2008.

PORTLAND, Ore. (AP) - Thousands of marchers carrying signs and beating drums paraded through the center of downtown in late winter rain on Saturday to protest the fifth year of the Iraq war.

Among the marchers was Oregon House Speaker Jeff Merkley, a leading Democratic challenger to Republican U.S. Sen. Gordon Smith, who is seeking a third term.

Merkley, surrounded by supporters, joined the chorus of demonstrators when they shouted it was time to get U.S. troops out of Iraq.

His main primary opponent, Portland lawyer and party activist Steve Novick, a longtime opponent of American involvement in Iraq, also marched.

"It's important to replace Sen. Smith because he has not taken a stand on bringing troops home," Merkley said. "We need to start bringing them home, starting now."

Smith initially supported the war but now opposes it, and has become one of the few Republican senators backing legislation to order troop withdrawals.

The World Without War march stretched through about a half dozen blocks at a time, closely watched by police. Some traffic delays were expected, but weekend traffic was light.

An estimate of the number who attended was not immediately available.

A similar march and peace rally last year attracted about 15,000. 

(Copyright 2008 by The Associated Press. All Rights Reserved.)