PROVIDENCE — About half of the 113 seats in Rhode Island’s overwhelmingly Democratic General Assembly will feature just one candidate on the November ballot, in large part because Republicans weren’t able to find anyone to run.Thirty-seven of the 75 House seats will have a single candidate in the general election, according to candidate filings with the secretary of state’s office. In the vast majority of cases, that will be the incumbent because the number of open seats is small this year.Candidates for Senate will also run unopposed in November in 20 of the state’s 38 districts.There are primaries in a few dozen House and Senate races.“I think it’s unfortunate for the voters that we weren’t able to find anyone to come forward,” said Mark Smiley, the state Republican Party chairman. “Many of the voters are looking for change but can’t quite make that leap of faith to be the person on the ballot to do it.”Smiley said the party is fielding candidates in the most competitive races and blamed the lack of challengers elsewhere in part on the master lever, which allows voters to select all the candidates from one party with a single ballot mark. The General Assembly this year passed legislation to abolish the master lever, but it won’t take effect until 2015.About a quarter of the voters in the 2012 elections used the master lever; three-quarters voted for Democrats.Smiley said at least a dozen potential candidates have said they wouldn’t run until the master lever was eliminated.“Hopefully in the next election cycle, with the master lever gone, we’ll be able to find more people willing to step forward,” he said.On the House side, there are Republicans running in 26 of 75 districts; that includes six incumbents. There are independents running in 13.On the Senate side, there are Republicans running in 11 of 38 districts, according to candidate filings. The GOP had five Senate seats during the 2014 session, but Sen. David Bates of Barrington is retiring and Sen. Dawson Hodgson of North Kingstown is running for attorney general. There are independents running in 12 Senate races.In the House, those running unopposed include Speaker Nicholas Mattiello and Majority Leader John DeSimone. In the Senate, President Teresa Paiva Weed drew a Republican challenger, business owner Mike Smith.Smiley said the party considers the following Democrats to be the most vulnerable: • Rep. Michael Marcello of Scituate, in District 41. He will face Republican Lillian Jean Delmonico, who serves on the Scituate School Committee, and independents Frederick Ferri and Robert Quattrocchi. • Rep. Larry Valencia of Richmond, in District 39. Michael Picillo, who has run previously for the seat, and Justin Price will meet in the GOP primary. • Rep. Samuel Azzinaro of Westerly, in District 37. He will face Westerly Town Councilor Caswell Cooke Jr. • Rep. Scott Guthrie of Coventry, in District 28. His challenger is funeral director Robert Nardolillo III. • Rep. Dennis Canario of Portsmouth, in District 71. He will face Norbert Rattay, who ran unsuccessfully for the Portsmouth School Committee in 2012. • Rep. Linda Finn of Middletown, in District 72. Former state Rep. Daniel Reilly filed for a rematch after being defeated by Finn in the last election.On the Senate side, Smiley said the Republicans are hoping that they have a shot against Democrat Donna Nesselbush in District 15 in Pawtucket. The Republican candidate is a retired Marine, Stephen Lemois; John Monahan filed as an independent.