Mainers still don’t know who their state’s 2nd congressional district will send to Congress in January, and a week after the election, things are getting more complicated, not less.

The race between the Republican incumbent Bruce Poliquin and Democrat Jared Golden remains close, with Poliquin ahead by roughly 2,000 votes, which is 0.7% of the votes cast.

Golden may be trailing, but he nevertheless appears to be on track to succeed. On Friday, Maine election officials started processing ballots for the state’s first federal race to employ its new ranked-choice voting system, which goes into effect when no candidate receives a majority of votes.

Under this new system, voters rank the candidates they want in order of choice. Because neither Poliquin nor Golden received more than 50% of the vote, the ME-02 race enters an “instant runoff.” Mainers in District 2 who voted for candidates other than Poliquin or Golden will now have their second, or even third, choice rankings counted. The system is largely believed to benefit Golden and it could be what tips the scales in his favor.

Maine voters approved ranked-choice voting by a slim margin in 2016, and lawmakers reacted promptly. After a 2017 advisory opinion by the Maine Supreme Court said they would rule ranked-choice voting unconstitutional if it were brought to them, the Maine legislature voted to delay ranked-choice voting’s implementation until 2021. Enraged supporters of ranked-choice voting organized quickly to add a people’s veto about the legislature’s delay to the June 2018 ballot. The veto passed, restoring ranked-choice to Maine just in time for this year’s midterms.

But today, ranked-choice voting finds itself once again enmeshed in legal drama. With the system expected to propel Golden past the GOP incumbent, the Portland Press Herald reports that Poliquin has filed suit in federal court, trying to stop the Maine secretary of state from proceeding with the ranked-choice count.

In his complaint, Poliquin asserts he has a “constitutional right to have federal election returns counted in accordance with traditional – and constitutional – procedures.”

What will come of the lawsuit, we don’t yet know, but the timing is raising eyebrows. Poliquin, a sitting congressman, is challenging a state law—twice approved by voters—after the election, once it appeared ranked-choice voting would favor his opponent.

As the battle in Maine’s 2nd continues to unfold, the outcome is likely to have national reverberations. If Golden were to win, it would not only be another Democratic House pickup, but it also would make him the first member of Congress to win through ranked-choice voting—a system some see as the future of democracy and others decry as unnecessarily complicated and unconstitutional.