After the recent conventions, McCain was capped at spending the $84 million in taxpayer funds allotted to him under the public financing system.
But the Arizona senator is getting help from the Republican National Committee, which has, so far, taken in $109 million more than the Democratic National Committee in fundraising money, according to Federal Election Commission documents.
Since 2007, the RNC brought in $219.2 million and spent $147.2 million, while the DNC brought in $109.8 million and spent $105.8 million.
Senate Majority Leader Harry Reid, D-Nev., made a personal appeal to Obama earlier this month, asking him to share some of his wealth to get senators re-elected, but Obama declined.
The Obama campaign so far has agreed only to let Senate Democrats use Barack and Michelle Obama and vice presidential candidate Sen. Joe Biden, D-Dela., in online appeals and direct mailers. Obama hasn't held joint fundraising events with House or Senate Democrats.
Meanwhile, Republicans are bragging about a surge in fundraising, following McCain's selection of Alaska Gov. Sarah Palin to join the Republican ticket.
"She's re-energized the base," Republican lawyer Ben Ginsberg told ABCNews.com recently, arguing Palin has helped the GOP raise a significant amount of money.
The Republican National Committee reported taking in $1 million after Palin's acceptance speech at the convention, although the Obama campaign reported taking in $10 million.
Palin's selection has appeared to energize A-list celebrities in Hollywood, with actor Matt Damon saying her pick is "like a really bad Disney movie" and Streisand criticizing McCain's selection of Palin on her Web site.
Streisand originally backed Obama's primary rival Sen. Hillary Rodham Clinton, D-N.Y. But Streisand switched to support Obama when he clinched the Democratic presidential nomination.
"This calculated, cynical ploy to pull away a small percentage of Hillary's women voters from Barack Obama will not work," Streisand wrote on her Web page. "We are not that stupid!
"I believe John McCain chose Gov. Palin because he truly believes that women who supported Hillary, an experienced, brilliant, lifelong public servant, would vote for him because his vice president has two X chromosomes," Streisand said. "McCain's selection of Gov. Palin is a transparent and irresponsible decision, all in the name of trying to win this election."
ABC News' Tahman Bradley contributed to this report.