PHILADELPHIA -- With his party facing losses in next month's election, President Barack Obama pressed his argument Sunday that the opposition is trying to steal the election with secret special-interest money, including possibly from foreign companies.
In a speech to a large rally in Philadelphia and in a new television advertisement, Mr. Obama and the Democrats escalated their efforts to present the Republicans as captive to moneyed interests. But Republicans and their allies fired back, dismissing the assertions as desperate last-minute allegations with no evidence to back them up.
"You can't let it happen," Mr. Obama told thousands of supporters gathered on a school lawn in a predominantly African-American, working-class neighborhood of northern Philadelphia. "Don't let them hijack your agenda. The American people deserve to know who's trying to sway their election and you can't stand by and let the special interests drown out the voices of the American people."
Mr. Obama appeared along with Vice President Joe Biden, Gov. Ed Rendell and two statewide Democratic candidates -- Dan Onorato, the Allegheny County executive who is running for governor, and U.S. Rep. Joe Sestak, who is running for the U.S. Senate.
It was Mr. Obama's first public political event in Pennsylvania since he took office in January 2009, according to The Associated Press.
Today, he heads to Florida, then later in the week will hold two town hall-style sessions aimed at motivating his party's base before heading to Delaware, Massachusetts and Ohio.
The president has increasingly used the issue of campaign finance to motivate his supporters as the elections grow nearer and polls signal trouble for Democrats. With his party outmatched in advertising sponsored by groups that do not have to disclose the source of their financing because of a free-speech Supreme Court decision earlier this year, Mr. Obama has suggested that the sponsors of campaign advertising have sinister motivations.
"You don't know," he said. "It could be the oil industry; it could be the insurance industry; it could even be foreign-owned companies. You don't know because they don't have to disclose. Now that's not just a threat to the Democrats; it's a threat to democracy."
The president's recent speeches were matched by a new advertisement by the Democratic National Committee attacking the United States Chamber of Commerce and Karl Rove and Ed Gillespie, two former aides to President George W. Bush who have helped groups supporting Republican candidates.
The ad calls Mr. Rove and Mr. Gillespie "Bush cronies" and the chamber "shills for big business," then shows a woman having her purse stolen by a mugger in a parking garage. "They're stealing our democracy, spending millions from secret donors to elect Republicans to do their bidding in Congress," the narrator intones. "It appears they've even taken secret foreign money to influence our elections."
The Democrats have offered no evidence that the chamber is using foreign money to influence the elections. The chamber has overseas affiliates that pay dues to the main organization but says it segregates those funds from any used for electioneering.
"The DNC is going to exhaust itself trying so hard to change the political conversation," Tom Collamore, the chamber's senior vice president of communications and strategy, said in a statement. "Its ad attacking the U.S. Chamber is a blatant attempt to avoid a serious discussion of Americans' top priority -- creating jobs and growing the economy. The ad is ridiculous and false."
David Axelrod, the president's senior adviser, was asked by Bob Schieffer on CBS's "Face the Nation" if he had any evidence that the chamber was using secret foreign funds to influence the election. "Well, do you have any evidence that it's not, Bob?" Mr. Axelrod replied. "The fact is that the chamber has asserted that, but they won't release any information about where their campaign money is coming from. And that's at the core of the problem here."
The DNC spokesman, Hari Sevugan, likewise offered no evidence.
The chamber is hardly the only organization playing a role in the campaign that has international affiliations and gets money from foreign institutions. Among others are groups on the political left like the AFL-CIO and the Sierra Club. The law bars them from using foreign money for domestic political activity.
Mr. Rove and Mr. Gillespie shot back in separate Sunday show appearances.
"Have these people no shame?" Mr. Rove said on "Fox News Sunday."