Jonathan J. Cooper, Associated Press
Candles are displayed atop the Oregon state Capitol in Salem on Monday, Sept. 30, 2013 in honor of the building's 75th birthday on Oct. 1. They are only two seats, but the Democratic gains in the Oregon Legislature could make a world of difference.

SALEM, Ore. — They are only two seats, but the Democratic gains in the Oregon Legislature could make a world of difference.

After picking up one seat in the state House and one in the Senate, Democrats have moved the Legislature decisively to the left. With a razor-thin margin, a second Senate seat also could flip to the Democrats' control.

The partisan shift opens the door to gun control, environmental regulations, voting rights and other ideas that liberals have tried and failed to pass in the last four years.

"Our political plan for this election cycle was really all about establishing a pro-conservation majority in the state Senate," said Doug Moore, director of the Oregon League of Conservation Voters. "And that happened."

Democratic Sen. Alan Bates was re-elected in a closely divided Southern Oregon district, and Democrat Sara Gelser defeated Republican Sen. Betsy Close in the Corvallis and Albany area.

Those victories give Democrats, at worst, a 17-13 edge in the Senate, up from the 16-14 margin they have had for the past four years. Centrist Democratic Sen. Betsy Johnson occasionally sides with all 14 Republicans, particularly on business, environmental and gun legislation, locking the Senate in a 15-15 tie. Sixteen votes are required to pass a bill.

With the outcome of one Senate race still uncertain, the numbers could shift even more. In Washington County, Republican Sen. Bruce Starr and Democratic challenger Chuck Riley were separated by just 13 votes out of 36,000, with thousands left to count.

Democrats won nearly every battleground seat in the House, picking up one seat previously held by Republicans. They now control the House 35-25.

Moore said potential environmental legislation could include an extension of Oregon's low-carbon fuel standard, which is set to expire after never being fully implemented. Environmentalists also are likely to push for restrictions on toxic chemicals and legislation to address climate change, but he also sought to tamp down expectations, noting the Democrats still won't have enough votes to pass a carbon tax, which would require a three-fifths supermajority.

"I don't want to predict that everything's going to be sunshine and rainbows and flowers," Moore said.

Gun-control advocates have already signaled their intent to push for a stricter background-check requirements, and they may find better results with the addition of a supportive Senate Democrat. A bill requiring background checks for private gun sales fell short this year.

Another bill that fell short in the Senate would have changed the way Oregon handles payouts in class-action lawsuits. A House-passed bill would have required companies that lose or settle a case to pay into a legal aid fund if some victims don't claim their portion of the settlement. It died in the Senate, but the bill may find greater success with an additional Democrat or two.

Similarly, Democratic Secretary of State Kate Brown's effort to automatically register hundreds of thousands of new voters using driving records could be helped by additional Democrats.

The Democratic victories also mean Sen. Peter Courtney of Salem is likely to extend his run as Oregon's longest serving Senate President. House Speaker Tina Kotek, D-Portland, says she'll run again for the top job in the House.

Republican Sen. Jackie Winters said she wasn't ready to predict whether the Senate would take a strong left turn.

"After campaigns the biggest need is to try to bring about some healing," Winters said. "Because campaigns can get very very ugly, and I think these were."