(Carolyn Kaster ~ Associated Press)
With just six weekends left before Election Day, both men also were devoting considerable time to raising campaign cash to bankroll the deluge of ads already saturating hotly contested states. Baseball great Hank Aaron was supplying the star power at two Obama fundraisers in Milwaukee while Romney headed to San Diego and Los Angeles to tap into West Coast cash, if not votes.
With running mates Joe Biden and Paul Ryan campaigning in New England and Florida, respectively, the presidential campaign was spread far and wide -- both geographically and strategically. Biden revved up union activists poised to canvass for votes in New Hampshire while Ryan appealed to Hispanic voters in Miami and talked space policy in Orlando.
It was Obama's first visit to Wisconsin since February, and the president was intent on shoring up support in Ryan's home state. Obama won Wisconsin easily in 2008 and recent polls have him ahead by single digits, but Ryan is popular.
"We've always thought that Wisconsin would be harder for us this year than it was four years ago," said Obama campaign spokeswoman Jennifer Psaki.
In advance of Obama's visit, Romney's campaign made the argument that Obama's failure to turn around the economy had Wisconsin voters looking for a different path. Republican Gov. Scott Walker said the president had a "Wisconsin problem." The state's 7.5 percent unemployment rate is below the national average, but its manufacturing industry has been hit hard in recent years.
The Republican National Committee released a web video, "Since You've Been Gone," highlighting recent GOP organizing efforts in the state and Walker's success in fending off a recall election there.
Ryan, campaigning in Miami's Little Havana neighborhood, reinforced Romney's argument that Obama hasn't been able to make needed changes in Washington, poking at the president's recent comment that it's hard to change Washington from the inside without mobilizing public pressure on Congress from the outside.
"Why do we send presidents to the White House in the first place?" Ryan asked. "We send presidents to change and fix the mess in Washington, and if this president has admitted that he can't change Washington, then you know what? We need to change presidents."
He also faulted Obama for a "policy of appeasement" toward the Castro regime in Cuba, saying all the president had done was "reward more despotism."
Obama has eased restrictions to allow Americans to travel to Cuba and to let Cuban-Americans to send money to family on the island. But the president has stopped well-short of discussing lifting the 50-year-old economic embargo, which is widely viewed in Latin America as a failure and has complicated U.S. relationships in the region.
Psaki said the president had supported democracy movements on the island and worked to give people there more say in their futures.
In an appearance in Orlando, not far from Florida's space coast, Ryan criticized the president for putting the U.S. space program "on a path where we are conceding our global position as the unequivocal leader in space." The Obama campaign responded that Ryan has proposed deep cuts in spending for space exploration.
Underscoring the importance of grassroots efforts in the campaign's final days, Biden rallied union workers at a Teamsters union hall in Manchester, N.H., saying their organizing work would be the "antidote" to millions spent on advertising by Republican-leaning super PACs.
Biden said it was because of unions that the U.S. has a strong middle class, and he accused Romney and Ryan of having "a completely different value set, a completely different vision."
"They're doubling down on everything that caused the economic crisis in the first place," he said.
Romney is dedicating most of this weekend to courting donors in California -- a state that he's not trying to win. He attended a private fundraiser in suburban San Francisco Friday night and planned to attend at least two more on Saturday in San Diego and Los Angeles.
The GOP nominee is feeling fundraising pressure: Last month, for the first time, Obama and the Democratic Party raised more than Romney and the Republican Party, $114 million to $111.6 million.
Romney's schedule -- particularly his focus on fundraising over traditional campaigning with voters -- has caught the attention of conservative opinion leaders.
"The logic of Romney's fundraising has seemed, for some time, slightly crazy," conservative Wall Street Journal columnist Peggy Noonan wrote recently. "He's raising money so he can pile it in at the end, with ads. But at the end will they make much difference?"
Facing such criticism, the Romney campaign added a stop in Colorado late Sunday and will launch a three-day bus tour through Ohio on Monday. Over the past week, the Republican nominee attended just three public rallies, one televised forum and delivered a speech to the Hispanic Chamber of Commerce in Los Angeles.
As Romney was preparing to board his flight from San Francisco to San Diego, a reporter asked whether he was going to begin campaigning more aggressively. Romney smiled, said nothing, and walked away.
Associated Press writers Jennifer Kay in Miami, Steve Peoples in San Francisco and Holly Ramer in Manchester, N.H., contributed to this report.