By Emily Cadei, CQ Staff

Illinois Sen. Barack Obama ’s move to help New York Sen. Hillary Rodham Clinton pay off her presidential campaign debt is making headlines, but there are a handful of other former Democratic primary rivals who could use his assistance, as well.

Of those now defeated presidential hopefuls, Clinton has by far the most debt – approximately $10 million owed to vendors plus $12.2 million in personal loans she made to her campaign. And Obama’s statement Tuesday urging his top fundraisers to do what they can to help Clinton came as no surprise. Earning a spot in her good graces could be critical for the soon-to-be Democratic presidential nominee, as he seeks to consolidate party support moving into the general election against Republican Sen. John McCain of Arizona.

But what about former North Carolina Sen. John Edwards, New Mexico Gov. Bill Richardson , and Sens. Christopher J. Dodd of Connecticut and Joseph R. Biden of Delaware? All four have been left to deal with their own debt, even though three of them — Edwards, Dodd and Richardson — offered ringing endorsements of Obama before Clinton called it quits.

A spokesman for Obama acknowledged that the campaign has not made any appeals to its fundraisers to help anyone but Clinton.

The outstanding debt among the Democratic presidential challengers, as of May 31:

• Sen. Hillary Rodham Clinton — $22.5 million

• Sen. Joseph R. Biden — $1.2 million

• Sen. Christopher J. Dodd — $387,000

• Gov. Bill Richardson — $285,000

• John Edwards — $21,000 (The Edwards campaign, however, did not include in its debt tally outstanding loans totaling $1.4 million.)

Candidates cannot shut down their campaign committees until they have retired all their debt. Many presidential campaigns from years past -- including Howard Dean’s 2004 presidential committee and even Clinton-Gore ‘96 -- still exist and are carrying a negative balance. Candidates are allowed to raise money even after their campaign has concluded, as this current crop of also-rans continue to do.

Clinton, in fact, sent out an e-mail to supporters today assuring them that while their relationship would endure, “there’s something else -- less endearing and I hope less enduring -- that our campaign has left behind: our substantial campaign debt.”

Wrote Clinton, “I am asking once again for your help ridding our campaign of debt so we can keep fighting together.”