With calls for Hillary Rodham Clinton to drop out of the Democratic primary race multiplying, Barack Obama refused to join the chorus this weekend. Instead, the Illinois senator focused on his plan for economic recovery during his campaign's "Road to Change" tour through Pennsylvania.

Indicating that he expects the campaign to continue at least into May, Obama has released new TV ads in the next three states to weigh in on the Democratic race -- Pennsylvania, Indiana and North Carolina -- all focused on the failing economy and what Obama would do to help middle- and working-class Americans.

In "Nothing's Changed" running in Pennsylvania, Obama accuses oil companies of gouging customers at the gas pump and promises to change the system if elected. "Since the gas lines of the ‘70s, Democrats and Republicans have talked about energy independence, but nothing’s changed," Obama says, as old footage of long lines at fuel stations appears onscreen. "I don’t take money from oil companies or Washington lobbyists, and I won’t let them block change anymore," he adds.

His claim to eschew oil company funds sparked protest from the Clinton campaign, which sent out an e-mail Friday accusing Obama of "false advertising." The e-mail cites data from the Center for Responsive Politics apparently showing that Obama has received over $160,000 from oil and gas companies. Media critic Howard Kurtz jumped into the fray, pointing out that Obama "does not, as his campaign was quick to note, accept donations from corporate political action committees or lobbyists. The contributions flagged by Clinton's side come from individual executives and employees in the oil industry. That distinction, of course, may be lost on viewers who see Obama say flatly he takes no money 'from oil companies.'"

Another ad, "For Decades," was launched in Indiana late last week -- the first TV ad from any candidate to hit the Hoosier State. Obama, dressed in a leather jacket, stands in front of a closed-down factory and speaks directly to the camera about the need to create more jobs. Highlighting his efforts to help working Americans as a community organizer, Obama once again blames lobbyists for blocking reform in Washington that could help the working class. "I'm the only candidate who doesn't take their money, and they won't run my White House," he declares.

The campaign also launched its first ad in North Carolina on Friday, titled "Enough" (subscription). The ad, which previously ran in Iowa and other states, features Obama speaking to a large crowd about his plans to reward companies that keep jobs at home rather than exporting them overseas.