AUGUSTA – Maine’s system of public campaign financing, which has been enormously popular with legislative candidates, appears to be losing its luster in the wake of a U.S. Supreme Court ruling outlawing so-called matching funds in taxpayer-financed campaigns.

Figures from the state Commission on Governmental Ethics and Election Practices, which oversees campaign financing, show that 63 percent of Maine’s legislative candidates are drawing public funds through the state’s Clean Election Act in this year’s legislative campaign. That compares to 80 percent in the last election cycle and 85 percent in the previous one.

The participation rate among House of Representatives candidates is 62 percent this year, and 73 percent in the Senate.

The 2012 elections are the first under a new set of rules since the system of public financing was first used in 2002. Last year, the Supreme Court ruled that public funding systems cannot provide qualifying candidates with extra cash when their privately funded opponents outspend them.

A proposal to remedy the ruling was debated in the Legislature earlier this year but rejected, leaving the system without what many users considered a critical component. That may be a reason for the drop-off in participation, says a senator who has qualified and will use the system in her re-election bid this year.

“I think there has been a drop-off because some candidates are concerned that outside groups will launch negative attacks and there will not be matching funds to counter them,” said Sen. Lois Snowe-Mello, R-Poland.

“I am concerned this will happen to me, but feel strongly in the local grass-roots support and participation that my Clean Elections campaign represents,” said Snowe-Mello, who faces Democrat John Cleveland, a former Auburn mayor who also served four Senate terms in the 1990s.

Snowe-Mello reports expenditures of $1,772, but Clean Election payments and authorizations of $19,955.

Cleveland, whose campaign is funded privately, was among the biggest-spending candidates as of the last campaign finance reports, which were due Tuesday. Cleveland reported expenditures of $12,690 among all of the legislative candidates.

The largest campaign expenditures of any single candidate, $30,153, were reported by Colleen Quint, a Democratic Senate candidate from Minot who faces incumbent Republican Sen. Garrett Mason of Lisbon Falls. Mason, also privately funded, reported spending $17,495.

At the other end of the scale, some candidates report financial activity amounting to a few hundred dollars, and a few report no fundraising or spending yet for the November election.

This is considered a pivotal year in state legislative elections, with Republicans hoping to hang on to their House and Senate majorities and Democrats pushing to win back long-held majorities they lost two years ago. Maine has 186 House and Senate seats.