Are the Federal Election Laws keeping Clinton in the race?

John Fund has this interesting bit at today's WSJ's Political Diary:

Why is she still running? That's what Democrats are asking about Hillary Clinton in the wake of her disappointing performance in Tuesday's primaries.

One explanation is that something could always turn up once again to knock Mr. Obama off-stride, just as happened with the Rev. Jeremiah Wright and Mr. Obama's infamous "bitter" comments. Another possible reason is that she can't afford to leave the race. So far, Mrs. Clinton has loaned over $11 million of her own money into the campaign and still has substantial debts, including $4.5 million to her former chief strategist Mark Penn.

A little-known provision of the McCain-Feingold election law makes her exit a difficult question. If she hopes to get paid back for the money she lent her campaign, she can only accept repayment until the date of the Democratic convention in August. After that she can only accept a maximum of $250,000 from contributors.

"If she wants to be repaid, she'd have to move on that between now and the national convention," former Federal Election Commission chairman Michael Toner told U.S. News & World Report. The longer Mrs. Clinton stays in the race, the greater the chance she can still find some donors who have not already given her the maximum contribution allowed by law. Should she drop out, her chances of raising money from anyone effectively become zero. . . .