AUGUSTA, Maine — For the third consecutive year, hundreds of thousands of dollars in campaign money flooded into Maine just before an election in an attempt to sway the outcome.

In the fall, last-minute outside money was used to fuel the debate over Question 1, which dealt with whether to allow voters to register on Election Day. Mainers repealed a law that had ended the 38-year-old practice of same-day voter registration by a 60/40 vote.

Last year, the Virginia-based Republican State Leadership Committee spent $400,000 on negative mailers distributed to voters in five Maine Senate districts where Republicans were running close races. In all five races, the Republican candidate won.

And in 2009, out-of-state groups spent large sums leading up to a vote over whether to keep a newly passed law that allowed same-sex marriage. Mainers overturned that law by a 53/47 vote. The National Organization for Marriage, which has opposed same-sex marriage efforts in many states, including Maine, refuses to disclose its donors, even in the face of legal challenges. NOM spent nearly $2 million in Maine in 2009.

Mark Brewer, a University of Maine political scientist, said big money politics is still relatively new in Maine but also said it’s clearly becoming the norm.

“When I came to Maine from New York 11 years ago, I was struck by how Maine politics seemed nickle and dime,” Brewer said. “Now I think outside money is becoming more of an issue and I’m not sure there’s any going back.”

In recent years, it’s not necessarily the amount of money coming in, it’s the timing of those contributions and the uncertainty about exactly where those dollars are coming from, said Jonathan Wayne, executive director of the Maine Ethics Commission.

“We continue to be concerned in general that money can flow into a PAC in the last 13 days before an election and it’s not reported until 42 days after the election,” Wayne said.

In those last 13 days, Maine law requires PACs to file reports on any expenditures of $500 or more within 24 hours of the expenditure. Contributions received in that same period are not required to be reported.

Earlier this month, the final campaign finance report filed by the No on 1 political action committee showed that $250,000 of the $321,270 it raised came from the American Justice Partnership of Lansing, Mich. No on 1 supported the elimination of Election Day voter registration.

According to its website, that organization is a free-market organization that typically focuses on reforming the legal system. American Justice Partnership does not disclose its donors but has partnered with the Heritage Foundation and the American Legislative Exchange Council, two large national groups that have significant influence in conservative causes.

The Yes on 1 campaign, which raised a total of $840,155, received outside money, too, much of it from national union groups. The Washington, D.C.-based American Federation of State, County and Municipal Employees donated $25,000. The National Education Association and the Service Employees International Union donated $40,000 and $15,000, respectively.

Nearly half of the Yes on 1 money ($418,000) came from Donald Sussman, a billionaire hedge fund manager who is a Maine resident and also owns homes elsewhere. Sussman is married to U.S. Rep. Chellie Pingree, a Democrat.

A week before the election, the No on 1 campaign released advertisements that said “Mainers or outsiders from other states” were influencing elections here, a reference to Sussman and the unions.

Both campaigns relied on outside money, although the Yes on 1 side more clearly disclosed the source of its funding and met disclosure deadlines.

The Maine Ethics Commission levied a $3,251 fine against Secure Maine’s Ballot, the political action committee urging a “no” vote on Question 1, for not filing an expenditure report on time.

In 2010, the national group that spent $400,000 on Maine Senate races was fined more than $30,000, the largest ethics penalty in state history.

Brewer said fines have become part of the cost of doing business.

“The fines are pennies on the dollar for these groups,” he said.

Maine lawmakers admit that late money is a problem but also acknowledged that there is little will to make the necessary changes.

“It’s an unfortunate part of our politics. Anybody is free to say what they would like but when things come in so late that they avoid scrutiny and disclosure, that’s a problem,” said Rep. Michael Carey, the ranking Democrat on the Veterans and Legal Affairs Committee.

Sen. Nichi Farnham, R-Bangor, who is co-chairman of the Veterans and Legal Affairs Committee, said the Maine Ethics Commission works hard to constantly improve the process.

“It’s tricky as a candidate because you don’t necessarily count on it and it’s not always on message,” she said of advertisements from outside groups. “So in that sense it can work against you. These larger groups think they are helping and they may have the best of intentions, but it’s hard when you don’t have control.”

During the 2010 legislative session, the Maine Ethics Commission introduced a bill, LD 1546, that included a requirement for PACs and party committees to report contributions and expenditures greater than $1,000 within 24 hours.

The Legislature rejected that portion of the bill.