President Barack Obama set the stage Monday for what promises to be a contentious autumn with congressional Republicans, telling a Labor Day crowd in Detroit that he’s prepared to fight for a new job growth plan, defend organized labor and take steps to “restore the middle class in America.”

On the East Coast – in the early primary states of New Hampshire and South Carolina – Republican presidential contenders ripped Obama’s handling of the economy and pledged to take an economically battered America in a new direction marked by less spending and fewer regulations.

The sharply differing visions raised new questions about the ability of top Democrats and Republicans to tackle pressing budgetary and other issues while positioning themselves for what promises to be a bitterly contested campaign next year.

“These are tough times for working Americans,” Obama told a union-dominated crowd at a rally that included a warm-up act from Aretha Franklin. “The time for Washington games is over. The time for action is now.”

The president took credit for a series of controversial measures, including the health care overhaul, financial regulatory reform, the 2009 economic stimulus plan and the auto industry bailout.

“I’ve seen Detroit prove the cynics and the naysayers wrong,” he said, referring to the U.S. auto industry. “We’re fighting for good jobs with good wages … [and] an economy where hard work pays off and gaming the system doesn’t work.”

The president quoted a 1948 Labor Day speech delivered by President Harry Truman in Detroit. Like Obama, Truman ran for re-election that year against a largely hostile, Republican-dominated Congress.

“The gains of labor were not accomplished at the expense of the rest of the nation,” Obama said, quoting Truman. “Labor’s gains contributed to rest of the nation’s prosperity.”

Before Obama spoke, James Hoffa, president of the International Brotherhood of Teamsters, blasted congressional Republicans and urged the crowd to mobilize and help defeat the GOP at the polls in 2012.

“Everybody here has a vote,” Hoffa said. “Keep the eye on the prize. Let’s take these sons of bitches out and give America back to an America where we belong.”

As Obama rallied Democratic base voters in Michigan, Vice President Joe Biden headed to Cincinnati to attend an AFL-CIO Labor Day event. The AFL-CIO is a federation of 56 national and international labor unions.

Obama carried Michigan and Ohio in 2008, but both states – hit hard by the economic downturn – could prove challenging to keep in the Democratic column in 2012.

Meanwhile, five Republican presidential candidates were set to participate in the Palmetto Freedom Forum in Columbia, S.C. The event is hosted by Sen. Jim DeMint, R-South Carolina, a leader in the conservative tea party movement.

DeMint’s endorsement is one of the most sought after among 2012 GOP White House hopefuls, and his support would be a major boost for any Republican candidate in his home state’s pivotal early primary.

Former Massachusetts Gov. Mitt Romney initially declined DeMint’s invitation, saying he was concentrating on campaigning in New Hampshire, which holds an even earlier primary. But after falling behind newcomer Texas Gov. Rick Perry in some polls, Romney apparently changed his mind, opting to wrap up a pancake breakfast event in New Hampshire before traveling to Columbia for DeMint’s forum.

“The tea party is a powerful movement saying government’s too big, and I couldn’t agree more,” Romney told a crowd of roughly 450 people at the breakfast.

In addition to Romney, Rep. Michele Bachmann of Minnesota, businessman Herman Cain, former House Speaker Newt Gingrich and Rep. Ron Paul of Texas plan to attend the DeMint forum.

Perry was also slated to take part in DeMint’s forum but backed out Monday morning to return to Texas as it battles growing wildfires.

Perry did, however, participate in GOP Rep. Tim Scott’s town hall series in Conway, South Carolina, before returning home.

While in Conway, Perry sharply criticized Romney’s job growth record in Massachusetts.

“There’s one (GOP candidate) … that’s created jobs all over the world,” Perry said, referring to Romney’s oft-mentioned record in the private sector. “But while he was the governor of Massachusetts, he didn’t create very many jobs.

“We cannot choose a nominee … that is going to blur the lines,” Perry added. The GOP needs “someone who has a very stark difference [with] the president of the United States … and I would suggest to you I’m that person.”

Two other candidates not appearing at the event are also on the campaign trail Monday. Former Utah Gov. Jon Huntsman, drawing new attention after announcing his economic plan last week, wrapped up five days of events in New Hampshire with a parade and a picnic, and former Sen. Rick Santorum of Pennsylvania held three events in South Carolina.

Former Alaska Gov. Sarah Palin – who has not announced whether she will run for president – was in New Hampshire on Labor Day after three days in Iowa.

“We’re up against … Barack Obama’s very strange fundamental transformation of the country that we so love,” Palin said. “We don’t need a transformation. As you know, we need a fundamental restoration of all that is good and strong and free in America.”

CNN’s Alan Silverleib, Shawna Shepherd and Paul Steinhauser contributed to this report.