|Obama called on his supporters to stay as inspired as they were when they helped elect him in 2008 [AFP]
Barack Obama has launched a series of campaign rallies across the US in a bid to reignite voters' enthusiasm in the run-up to midterm elections in November.
He drew thousands of college students at the University of Wisconsin on Tuesday for an outdoor rally aimed at energising young voters who backed him when he swept into the White House in the 2008 presidential election.
But polls show his Democratic party could lose its current majority in congress in the November 2 vote to the rival Republicans, and Obama urged his supporters to build more momentum for the Democrats.
"I need you fired up," he said to loud applause.
"We need you to stay fired up. Because there is an election on November 2 that is going to say a lot
about the future - your future and the future of our country.
"We can't let this country fall backwards because the rest of us didn't care enough to fight."
Obama's stop in the central US state of Wisconsin is part of a four-state tour aimed at drumming up support among his party's base, young voters and independents.
In addition to Wisconsin, Obama is also visiting New Mexico, Iowa and Virginia - all states he won in 2008 and likely will need again in his expected re-election campaign in 2012.
Obama took office in January 2009 with a large Democratic majority in the House of Representatives and an effective 10 seat edge in the senate, counting two political independents who vote with the Democrats.
However, with the US economy recovering at a snail's pace and the president's approval ratings hovering in the mid-40s, the Republican party could be set to make big gains in the November vote.
All 435 seats in the House and 36 of 100 seats in the Senate are at stake in what is known as a midterm election, so-called because it falls half way through the four-year presidential term.
Burgeoning Tea Party
Republicans, benefiting from the burgeoning conservative Tea Party movement, have generated high turnout in primary elections, creating an advantage for the party in enthusiasm about voting.
But Obama called on his supporters on Tuesday to stay "fired up" and as inspired and involved in the upcoming election as they were two years ago.
He also underscored that his policies had indeed brought about change, citing his health reform bill, another bill aimed at Wall Street, and his decision to end combat operations in Iraq.
"I know times are tough right now, I know that it sometimes seems a long way from the hope and excitement that we felt on election day," he said.
"You elected me to do what was right - that was change you could believe in.
"We are bringing about change, and progress is going to come - but you have to stick with me... change is going to come for this generation."