SEATTLE — Practically ordering cheering supporters to vote, even though he’s not on the ballot, President Barack Obama declared Thursday that the Nov. 2 congressional elections will set the direction of the nation “for years to come.”

To hoots and hollers from a crowd of 10,000 in Seattle reminiscent of the massive rallies of his presidential run, Obama pleaded with voters to reach back for the enthusiasm they felt then, and go to the polls to stave off a Republican rout.

“If everybody that voted in 2008 shows up in 2010, we will win this election. We will win this election. But you’ve got to come out and vote,” Obama said, his voice hoarse from a cold as he yelled over the applause.

“You need to go right after this rally, fill out that ballot and mail it in today,” the president said. “Not tomorrow, not the next day, but today. Let’s get this done.”

Obama has vigorously stepped up his campaigning in recent days with fellow Democrats facing the specter of losing control of the House or Senate — or both — to Republicans on Nov. 2. His trip is taking him through Oregon, Washington, California, Nevada and Minnesota.

He spoke in a packed arena. An additional 3,000 people who couldn’t be admitted were in an overflow area set up outside in the University of Washington’s football stadium. The president made sure to speak first to those standing outside in the damp, chilly weather.

Obama ran through the stadium tunnel onto the field, reveling like a true sports fan in that experience. “I liked doing that,” he said.

On a four-day West Coast swing, Obama was campaigning in Seattle for Sen. Patty Murray of Washington, who is locked in a close race with Republican Dino Rossi. Obama said Murray has been a problem-solver for her state.

Still, Obama acknowledged that economic problems make this a tough election cycle for Democrats.

“There’s no doubt this is a difficult election. It’s because we have been through an incredibly difficult time as a nation,” the president said. He challenged voters to decide, in his words, if they want to stick with progress or return to Republicans and failure on Election Day.

“It’s up to you to say we are not buying what you are selling. We tried it before, it did not work, we are not going back,” the president shouted.

He told the Seattle crowd that the upcoming elections “will set the direction of this state and of this country for years to come.”

Obama has been stressing the same message for weeks, and aides say he would stick with it throughout his final flurry of campaigning. It is part of a tricky balancing act for the White House — deploying Obama to the right places to stir up enthusiasm and recruit first-time voters from two years ago, yet trying to keep people from viewing the election as a referendum on him and the battered economy.

Half of likely voters say Obama will have no effect on how they vote in their House races, according to a new Associated Press-GfK poll. Yet almost as many say they will, in fact, use their House vote in part to send a message about Obama — 26 percent to oppose him, 23 percent to support him.

Less than two weeks from the election, the question appears to be whether Republicans will enjoy a wave election, in which virtually all the close races tip their way and tilt power in Washington, or will accept more moderate gains. Obama’s aides profess confidence that Democrats will retain power but know all the factors working against them: near-10 percent unemployment, a history of midterm losses for the party of the president in power and public frustration with the slow economic recovery.

Ben Feller reported from Washington.