It is against the law for a candidate for federal office to take political contributions from foreigners.

But a potential "loophole" could help at least one high-profile candidate in the 2008 presidential race: It is perfectly legal for a candidate for federal office to use personal income earned in foreign countries — or personal income earned by a spouse in foreign countries.

As Hillary Clinton marches at the front of the pack of Democratic presidential contenders, she occupies a unique position among the field of candidates from both parties.

The New York senator has access not only to her own wealth, but also to the bankroll of her wealthy husband, former President Bill Clinton, who has capitalized greatly on his résumé since leaving office in 2001 and whose income has been significantly enhanced through speeches made in foreign lands.

Financial records released Thursday showed that by the end of last year, Hillary and Bill Clinton had between $10 million and $50 million in jointly held accounts, and the former president had earned $41.7 million in speaking fees since leaving office — including $10.2 million in speaking fees last year alone.

And two-thirds of the former president's income from speeches — more than $27 million, including $6.6 million in 2006 — has been for speaking engagements overseas.

And that poses a problem, said Cleta Mitchell, a campaign finance attorney at the Foley and Lardner firm in Washington, D.C.

"Do I think that's an issue? You bet. ... There ought to be enough public human outcry, that he says, that she says, they won't put any money ... received from foreign governments in our joint bank account," said Mitchell, who represents Republican clients. She said that also should go for any foreign businesses and companies that don't have a principal place of business in the United States.

According to Sen. Clinton's financial disclosures, Bill Clinton has been paid over the years by foreign celebrity speaking and publicity companies, technology companies, financial firms, banks, business associations and academic organizations, some of which were working on behalf of public institutions.

Hillary Clinton would be able to use up to half of any jointly held assets with her husband, said a Federal Election Commission official, who asked not to be identified due to office protocol in discussing federal election law.

The official pointed to the section of code that governs jointly held assets, saying if there is a joint asset — such as a joint checking account — and there is no specific designation of how much each spouse is entitled to, a candidate is eligible to use up to half of that asset to pay for his or her campaign.

That means Hillary Clinton could spend money earned by Bill Clinton while speaking in Paris, Hong Kong, Bogota or Dubai, just a few of the places overseas where the 42nd president has been paid to deliver a speech.

So far, campaign spending records show that Hillary Clinton has not spent any of her personal wealth in pursuit of the presidency. Asked if her campaign intended to use any of the joint wealth accumulated from her husband's speaking events, campaign spokesman Phil Singer said, "We're getting into hypothetical territory on this. If we've got something to say, we'll call you back."

Among the current crop of presidential candidates, Bill Clinton's speaking engagements are the most identifiable source of foreign income that could be used as campaign funds, although nearly all of the candidates are wealthy in their own right with sources of income that are likely to include foreign business.

Republican candidate Mitt Romney built his wealth, estimated at between $190 million and $250 million, as chief executive of a global investment firm. Other wealthy candidates include: Democrat John Edwards, who was well compensated as an executive at a hedge fund following his unsuccessful 2004 vice presidential campaign alongside Sen. John Kerry; Rudy Giuliani, the former New York mayor who went into consulting work after leaving office; and possible independent candidate Michael Bloomberg, the current New York City mayor, who made his riches as the head of a global business media empire.

Mitchell said she anticipates an outcry from liberal camps over the source of Republicans' wealth once documents are released later this month. Conversely, she said she doesn't think the Clintons' situation will make much noise.

"What I do have a problem with is people who will criticize Mitt Romney for creating wealth and jobs for people all over the world ... but they won't criticize Bill Clinton," who is cashing in on his public image, she said.

Joan Hoff, a presidential scholar at the University of Montana and a self-described liberal Democrat but no friend of the Clintons', said the former president's speaking fees might be his wife's edge in a race that is quickly shaping up to far exceed the cost of the 2004 presidential campaign.

"In this system, it's an absolute advantage. Money wins the primaries, and it may be that she's coming by hers in a kind of circuitous way, but it isn't unfair in the sense that anybody that can raise the money is the winner," Hoff said.

Brookings Institution scholar Stephen Hess said he is skeptical about the prospect of Clinton using her husband's wealth to bolster her campaign.

"The Clintons will not dip into their own money," predicted Hess, who has worked in both Republican and Democratic administrations. "They're a virtual fundraising machine, and have been for two decades. They don't start from scratch. They start from a Rolodex of people who have been contributing to them for many, many years."

Hillary Clinton had raised $36 million for her campaign and had $30.9 million in hand at the end of March, the last reporting period. The candidate closest to Clinton in the fundraising category was Illinois Sen. Barack Obama, who had taken in $25.7 million and had $19.1 million in hand.

The former president has seen some criticism for his choices of speaking events. A 2002 speech in Shenzen, China, was paid for by the JingJi Real Estate Development Group, which was run by a communist official, according to news reports. And in 2005, Clinton gave a speech in the Bahamas paid for by the Switzerland-based Serono International — a division of the German pharmaceutical Merck — while it was under federal investigation for U.S. business practices.

But Hess said that he's not concerned about the source of funds for Bill Clinton's speaking engagements.

"There's no secret about where Bill Clinton speaks, who pays for it and indeed — because it's so well covered [by the press] — what he actually says," Hess said.

"I don't see anything wrong with it, except that sometimes the amount of money that he gets for a speech ... seems a little tacky," Hess added. For instance, the Fortune Forum — an international aid event — paid Clinton $450,000 for one speech given in London on Sept. 26, 2006.

"Though it wouldn't look good if he was getting money from the government of Sudan," Hoff said, none of the Senate records indicate that is the case.

According to the Senate records, the former president's income over the past six years has far outpaced that of his wife.

Hillary Clinton took in about $9.8 million between 2000 and 2006 in addition to her government salary, most of which came from book advances and royalties from her 2003 book, "Living History." She also received $32,323 in royalties from her 1994 book, "It Takes a Village," which the records state were donated to charity.

The Senate financial records show a clearly increasing trend for the Clintons' joint assets, which included one joint deposit account and — until earlier this year — a blind trust, which is a type of stock investment that politicians use to prevent concerns over conflict of interest. A typical agreement must be approved by ethics overseers, and says that financial managers can only disclose the value of the trust; they cannot disclose the types of investments managers are making.

While not making it into the 2006 disclosures, the Clintons have since dissolved the blind trust in order to remove any possible ethical questions that could come up during the campaign, officials in Hillary Clinton's campaign said. The money was said to be reinvested in less lucrative savings accounts and treasury bonds.

In 2000 Hillary Clinton claimed a Citibank joint checking account valued between $50,001 and $100,000, and a blind trust valued between $500,001 and $1 million. By 2006, the Citibank deposit account was valued between $5 million and $25 million, and the blind trust was reported to have grown also to a value somewhere between $5 million and $25 million.

That means that their current joint wealth is valued somewhere between $10 million and $50 million. And in the six years since Bill Clinton left office, the Clintons' wealth grew somewhere between $8.9 million and $49.4 million. Said in another way, their joint wealth grew anywhere from nine to 90 times larger from 2000 to 2006.