The downtown stretch of Waterville is pictured on Feb. 8, 2019. Credit: Linda Coan O’Kresik / BDN

A Republican primary for a key Maine Senate seat is headed to ranked-choice runoff after no candidate received more than 50 percent of votes on Tuesday, with a sitting lawmaker best positioned to prevail.

In Senate District 16, which includes Waterville, Winslow, Fairfield, Oakland and Albion, Rep. Mike Perkins, R-Oakland, led with 44 percent of votes, compared with 38 percent for Kevin Kitchin and 17 percent for Mark Andre.

The race will go to a ranked-choice runoff between Perkins and Kitchin, with the second-choice votes from Andre supporters to be redistributed. The runoff, which will be conducted by the Maine secretary of state’s office, could take place Thursday or Friday. Ranked-choice voting is used for legislative primary elections but not general elections.

Perkins’ lead going into the runoff makes him the likely victor. If he prevails, he will face David LaFountain, the former Winslow and Waterville fire chief who advanced from the Democratic primary unopposed Tuesday. The district is one of several that could decide control of the Maine Senate this November.

Here are some of the other results from competitive primaries across Maine:

— In the new Senate District 10, which includes Brewer and nearly a dozen other towns in Penobscot and Hancock counties, Rep. Peter Lyford, R-Eddington, led Dedham businessman Robert Cross in the Republican primary. Democrat Ralph Cammack, the former deputy fire chief from Brewer, also advanced to the general election. The seat leans toward Republicans.

— In the Democratic primary for Senate District 13, which includes most of Lincoln County, Cameron Reny, a school counselor from Bristol, led Newcastle lawyer David Levesque. Reny will face former Rep. Abden Simmons, R-Waldoboro, in the swing district that could decide control of the Maine Senate later this year.

— Rep. Holly Stover, D-Boothbay, easily held off a challenge from Thomas Moroney in House District 48, which includes the Lincoln County towns of Boothbay, Boothbay Harbor, Edgecomb, South Bristol, Southport and Westport Island. Stover will face Boothbay Harbor Selectman Tricia Warren in the general election.