AUGUSTA -- At least three candidates for governor are worried the state's public financing system will run out of money in the midst of their campaigns.

A Democrat, a Republican and a Green Independent all expressed their concerns Thursday to the Maine Commission on Governmental Ethics and Election Practices, either through a spokesperson or in writing.

At issue is a projected deficit in the fund, which has been raided in recent years to close state budget gaps.

Maine Commission on Governmental Ethics and Election Practices Executive Director Jonathan Wayne estimates the shortfall could range from $583,000 to nearly $1.8 million, depending on how many candidates qualify for the program.

Voters approved a citizen initiative in 1996 to create the system. It provides money for legislative and gubernatorial candidates to run for office without having to solicit funds from outside groups.

At this point, seven of the 21 people running for governor have expressed an interest in using public financing. To qualify, they have to raise $40,000 in seed money, collect 3,250 qualifying contributions of $5 or more and get 2,000 signatures if they are a party candidate or 4,000 signatures if they are unenrolled.

Jim Mitchell -- a lawyer who spoke on behalf of his wife, Senate President Elizabeth Mitchell, D-Vassalboro, who is running for governor -- said the system already provides bare-bones funding when compared to traditionally financed candidates.

The allotment for a general election is $1.2 million -- an amount that can be increased by matching funds if a privately financed candidate raises money in excess of that amount.

"The reality is these campaigns are underfunded," Mitchell told the commission.

Because they face the prospect of having to raise money if there's a shortfall, the Mitchell campaign and Sen. Peter Mills, R-Cornville, a Republican contender, have submitted a joint letter suggesting a way to address the problem.

In addition to being able to solicit money from individuals, the candidates want the power to raise an extra $50,000 to pay for fundraising staff, Mitchell said.

David Bright, campaign manager for Green Independent gubernatorial candidate Lynne Williams, agreed.

"He's right," he said. "It does cost money to raise money," he said. He also urged the commission to take an aggressive approach with the Legislature by making it clear it's not acceptable to reduce funding for the system any further. "The concept of clean elections, from day one, is you get better government," he said. "If we end up messing around with the election system, everything else the government does will be suspect."