Sagging in the polls as well as his fundraising, Chaka Fattah has turned to someone who seems to share neither of these headaches: U.S. Sen. Barack Obama.

An email this afternoon sent to Fattah supporters contained a plea from Obama to send "$500, $100, $50 or $25 right away, so Chaka can get his message to voters in this crucial week before the May 15th election."

Fattah, a seven-term congressman, kicked off the mayor's race as the frontrunner. But recent polls show him ranked third, behind Tom Knox and Michael Nutter. He also raised less money in the first four months of this year than any of his four Democratic rivals.

Enter Obama, via email.

"In 25 years of public service on the local and national levels, Chaka has never forgotten his early life lesson: the key to breaking the grip of violence in our most hard-pressed communityies is to replace desperation with hope," wrote the Illinois Democrat who wants to be president.

"To win this election, Chaka doesn't need to match the other candidates dollar-for-dollar, but he does need a strong push this week," Obama.

He went on to compare his own Senate race, in which he faced a wealthy opponent buying lots of TV time, to the challenge Fattah faces in the primary - in which Nutter has risen in the polls, and Knox, a millionaire health executive who has poured $8 million into his campaign, has been the frontrunner.

"By organizing a first-rate field operation and getting our supporters to the polls, we turned that conventional wisdom on its head," Obama wrote. "With your help Chaka can do the same thing."

Fattah today was beaming about the Obama message. "That was strong, wasn't it?" he said as he was leaving a campaign stop at the Reading Terminal Market.

This isn't the first time Fattah has turned to Washington for help. One of his TV ads includes footage of Bill Clinton praising him, and in the fall, the former president was the headliner at a fundraising event for Fattah's congressional campaign.

On the campaign trail, Fattah has been given to quoting Obama and comparing their life stories. And Fattah's key campaign strategist, Tom Lindenfeld, also helped Obama win his Illinois Senate seat - a point Fattah likes to make time and again.