PROVIDENCE, R.I. – Secretary of State Matt Brown has been running for the U.S. Senate on a clean government platform but now finds himself dogged by questions about donations his campaign received from Democratic parties in other states.

Brown re-ceived $25,000 from state Democratic parties in Hawaii, Maine and Massachusetts days before four of his top donors gave $30,000 to those parties. The donors had already given Brown the maximum they could under the law.

Critics accuse Brown’s campaign of arranging illegal donations, and on Wednesday, the Hawaii Republican Party signed a complaint asking the Federal Elections Commission to investigate the matter. Brown has said he did nothing illegal, but he’s returning the money because it created an “appearance problem.”

The contributions have shed light on a practice that campaign finance experts say is an increasingly common way of skirting federal campaign laws.

“This is a run-of-the mill campaign finance tactic,” said Nathaniel Persily, a University of Pennsylvania Law School professor who specializes in election laws.

Brown, Rhode Island’s top elections official, is one of two Democrats running for the seat held by Republican Sen. Lincoln Chafee. Chafee, a moderate in a heavily Democratic state, faces a conservative challenger in the primary.

The race is considered one of the best chances for Democrats to win a seat in the Republican-dominated Senate and has already become one of the most expensive in the nation. The four candidates have spent almost $3 million with the primary still six months away, according to the Center for Responsive Politics, a nonprofit, nonpartisan group that tracks campaign finances.

Brown has said that late last year, his campaign field director contacted the parties, asked them to contribute and offered to help them raise money in return. Brown describes the offer as a well-intentioned effort to help Democrats around the country.

But the treasurer of the Hawaii Democratic Party told The Associated Press earlier this month that the campaign and party struck a deal in which the party gave money to Brown in exchange for money from Brown supporters. She later said there was no deal.

Earmarking money for a specific candidate and funneling it through a third party to avoid the $4,200 limit on individual donations to campaigns is illegal under federal law, campaign finance experts say.

Many people legally give to multiple candidates or to both candidates and political parties.

It becomes illegal when donors give to a party – or other organization – with instructions that the money be sent to a particular candidate, said Larry Noble, executive director of Center for Responsive Politics and a former general counsel for the Federal Elections Commission.

“There’s a fine line between it being just a suggestion that you’ll help fundraise and it becoming an earmarked contribution,” Noble said.

It’s also hard to prove wrongdoing without someone involved in the deal confessing, Noble said. Still, eight of the 10 largest fines ever levied by the Federal Elections Commission were for donations given under someone else’s name, FEC spokesman George Smaragdis said.

Critics say the Brown campaign violated the spirit of the law even if no deal was made.

“It’s wrong, and they know it’s wrong, and they did it because they thought they could get away with it,” said Phil West, executive director of Common Cause of Rhode Island, a nonprofit, nonpartisan government watchdog.

Fundraisers and political scientists say plenty of other campaigns do it as well.

“The fundraising that happens here, happens around the country,” said Rick McAuliffe, a Rhode Island Democrat who raised money for John Kerry’s 2002 presidential bid.

Less than half of a percent of Americans donated to a federal campaign during the 2004 presidential election cycle, according to the Center for Responsive Politics.

To get the most out of those donors, campaigns hungry for cash often direct them to give to parties or other campaigns they support and hope those parties or campaigns will do the same for them. The practice is often called “donation swapping.”

“You constantly hear about candidates who are trying different ways to raise money, to get people, parties to raise money. It has to be an obsession if you run for office,” said Mary Boyle, Common Cause’s national spokeswoman.

Senate races in 2004 cost $1.3 million to $20.3 million, according to the Center for Responsive Politics. A recent University of Washington report predicted that this year’s candidates will need to raise at least $3 million each to have a chance of winning.

Campaign finance laws have undergone a number of reforms in the past decade. But West said none will be effective as long as candidates must privately raise millions of dollars to buy television time.

His group, Common Cause, advocates public financing for political campaigns to address the problem – as does Matt Brown.

“I think the given of American politics is that money pushes its way into the political process,” West said. “It’s almost like water finding a crack in the foundation of your house.”