The president started his day with a stop at a local doughnut shop and a Seattle home before heading to the rally, where a standing-room-only crowd awaited him.
The campaign event kicked off with remarks by Sen. Murray, as Obama stood by listening. Then Obama took the stage to raucous applause, practically ordering supporters to vote, declaring that the Nov. 2 congressional elections will set the direction of the nation "for years to come."
"We need you fired up, Seattle, because in just a few days, your decision in this election is going to set the direction of this state and of this country for years to come," Obama said.
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.
After the rally, Obama headed back to Boeing Field and Air Force One, which took off just after 1:30 p.m., bound for his next campaign stop in San Francisco.
Obama's trip began 16 hours earlier, when he arrived in Seattle Wednesday evening, spending the night at a downtown hotel.
As the president's motorcade wound through Seattle on Thursday morning, he stopped at the Top Pot doughnut store at Fifth Avenue and Blanchard Street at about 9:30 a.m.
The president ordered a sampler of two dozen doughnuts to go, then shared a doughnut with Murray, declaring it "outstanding." He urged the other customers at the shop to vote in the upcoming midterm election before carrying the two boxes of doughnuts back to his motorcade.
The motorcade then headed to the View Ridge home of Erik and Cynnie Foss just before 10 a.m. Cheering crowds lined the streets on the way there, including a school that had apparently completely emptied out, so that the kids lined the neighborhood street on the way to the Foss family home.
After about 10 minutes in the Foss home, Obama came out to the backyard for a low-key event with an audience of about 30 women.
The president trumpeted his efforts to help women in the workforce as he looks to rally key Democratic constituencies ahead of the Nov. 2 election.
As the economy has changed, Obama says women have made "enormous strides" and now constitute more than half of the workforce. Obama says that means women's issues are now middle class family issues.
But the president also acknowledged he hasn't done enough to sell policies like health care and the stimulus bill to voters who seem poised to resoundingly reject them - and Democrats - on Nov. 2.
"I take some responsibility for that," said Obama, as he strives to help fellow Democrats keep control of Congress.
The president also reminded his audience that the recession began before he entered the White House, and said he has focused his efforts on ending it.
"We lost almost 8 million jobs before any of the economic policies I put into place were able to be put into effect," Obama said.
After the Thursday morning chat was done, he joined Sen. Patty Murray at the University of Washington's Hec Ed Pavilion at 11:30 a.m. for a public rally in support of Murray's re-election bid.
The president has created quite a buzz on the UW campus, where some students camped out since Wednesday night in hopes of getting in.
Outside the pavilion, some protesters mingled with the crowd before the rally, including Lisa Marcus, who carried a doll covered in fake blood.
Holding a sign saying "War is Madness," she called for an end to the war in Afghanistan.
"I think the war is horrible, and everyone should really should know that in their hearts," she said.
Other protesters called on the administration to abandon the "don't ask, don't tell" policy for gays and lesbians serving in the U.S. armed forces.
Obama has already campaigned on Murray's behalf this year - he was here in Seattle on Aug. 17 - but returns as polls show the race is tight between Murray and Republican challenger Dino Rossi.
Obama hopes to help keep Murray and a Democratic majority in the Senate, as it's what he needs to help get his agenda through Congress in the final two years of his term.
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 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.
Obama's main roles are to raise money for the party, draw votes and media coverage for candidates in tight races, entice volunteers to knock on doors for scores of lesser-known candidates and try to shape the national election debate.
The Associated Press contributed to this story.
Watch Obama's backyard speech on the country's economy: