U.S. Sen. Barack Obama, D-Ill., continued positioning himself as the anti-war presidential candidate Sunday in Ames, attempting to distance himself from a crowded Democratic primary field one day after he formally announced his bid for the White House in 2008.

Before a lively crowd estimated at 6,000 in Hilton Coliseum, the 45-year-old wunderkind politician touted his plan to end the increasingly unpopular Iraq War on the second day of his presidential campaign. The animated rally was an opportunity for Obama to contrast himself with Democratic front-runner, Sen. Hillary Clinton, D-N.Y., who he said offered no specific way out of the nearly four-year-old conflict.

“I am proud that I opposed this war from the start,” Obama said. “I thought it was a tragic mistake. But what I am also proud of is that I have put forward a very specific plan to bring home our combat troops [and] redeploy them out of Iraq by March 31 of 2008.”

On Saturday, Obama threw his hat in the presidential ring while standing on the steps where Abraham Lincoln warned that a divided nation could not stand. On Sunday, after the first-term senator made his way across Iowa, he called for ordinary Americans to re-enter politics, something he said has been absent. With grassroots activism, Obama said, he and his supporters can “transform the country.”

Were Obama to succeed in his drive for the White House, he would alter the American political landscape, becoming the first black president in the nation’s history.

“I want this campaign to be a vehicle for all of you to participate in ways that we haven’t participated in for too long,” he said. “I want to see young people getting engaged and getting involved and bringing their energy and ideas to the process. I want to see people who’ve opted out of the process say ‘Maybe we’re going take a chance this time.'”

Obama’s call for populist political participation may be acknowledgment of Clinton’s more established and deeply rooted campaign and fundraising mechanisms. Obama may not be able to outspend his opponents, but he said he believes in “bottom-up” politics, getting average citizens involved in place of lobbyists and special interests.

“I am an imperfect vessel for your hopes and dreams,” Obama said. “I can be a part of this process, but I can’t do it alone. I am going to need all of you, and I hope that you guys decide that is something is worth doing.”

The energetic crowd – repeatedly interrupting the senator with outbursts of shouts and applause – was full of young and old, some familiar with the charismatic politician and some getting their first impressions.

Sebastian Yaklin, sophomore in aerospace engineering, said he showed up at the arena not knowing much of the young presidential candidate. He left impressed by Obama’s oration abilities, but wanting more in the way of substance.

“When you’re talking to people like this in a large group you’re just trying to appeal to a broad base,” Yaklin said. “And broad statements like improving health care and stuff like that doesn’t really show your voting record.”

Obama’s repeated statements opposing the war were substance enough for Augustus Lartius of Boone, though, who said the conflict was the No. 1 issue. Impressive, too, was the senator’s ability to connect with voters, he said.

“He doesn’t look like a politician to me,” Lartius said. “He looks like one of us.”

More coverage on the reaction to the Obama rally is available here. You can also view of a multimedia slideshow of the rally here.