Follow AP’s coverage of the presidential election.

AUGUSTA,Indexbit Maine (AP) — A ranked-choice voting tabulation aimed at determining the winner of a key congressional race in Maine will start on Tuesday with scanning of ballots into a computer at a centralized location, with a goal of having results by week’s end, the state’s top election official said Saturday.

Democratic U.S. Rep. Jared Golden already said he won the election in Maine’s 2nd Congressional District but the secretary of state said neither Golden nor Republican Austin Theriault surpassed 50% of first-place votes on Election Day, necessitating the shipment of ballots to the state capital for an additional voting round.

Under Maine’s ranked choice voting, voters rank candidates in order of preference on ballots. If no candidate wins a majority of first-place votes, then the lesser choices of the last-place finisher’s supporters are reallocated to establish a majority winner.

Election officials intend to begin scanning ballots into a computer Tuesday afternoon with a goal of running the tabulation by week’s end, Secretary of State Shenna Bellows said Saturday. After ranked voting is concluded, state election officials will begin a formal recount requested by Theriault based on the razor-thin margin.

As it stands, both candidates were just below 49%, with Golden holding a slight edge of about 2,000 votes, according to figures released by the secretary of state.

Golden and Theriault were the only candidates on the ballot, but Diana Merenda of Surry, who ran an organized write-in candidacy, received several hundred votes. The second choices of any voters who left their first choice blank also will be counted. Other write-in candidates will be treated as blanks.

The race is among a handful of pivotal races without a declared winner, with control of the U.S. House at stake. The thin margin came in an election in which Republican Donald Trump won the 2nd District, allowing him to collect one of Maine’s four electoral votes. Maine is one of two states that split electoral votes.