JUNEAU, Alaska (AP) — A candidate with the same name as Alaska’s incumbent U.S. senator advanced Tuesday to the general election in what will be one of the most closely watched races in the country this fall.

Dan J. Sullivan, who goes by Dan Sullivan, was among the top four finishers after the Aug. 18 primary and moved on to the November matchup, which is a ranked choice contest. The incumbent, Republican Sen. Dan Sullivan, and Democratic former U.S. Rep. Mary Peltola also have advanced.

The challenger Sullivan, a retired teacher from the island community of Petersburg, sued for a spot on the ballot and succeeded after a judge invalidated a decision by a top state elections official who said he had filed his candidacy with an intent to confuse voters. The allegation was driven by claims raised by the senator and his GOP allies. The state Supreme Court ultimately ordered Dan J. Sullivan eligible for the ballot.

While the challenger sought to appear on the ballot as Republican Dan J. Sullivan, the Division of Elections listed him as Daniel J. Sullivan Jr., with no party affiliation. The senator was listed as Dan S. Sullivan, Republican and incumbent.

President Donald Trump endorsed Sen. Sullivan for reelection and called the other Sullivan’s candidacy an attempt to trick voters. Dan J. Sullivan criticized the incumbent for embracing Trump’s endorsement and said the president was “more interested in raising tariffs on our allies than in lowering the cost of groceries, housing and energy.”

The Senate race was one of three major contests on Alaska’s primary ballot, which also featured races for the state’s lone U.S. House seat and governor.

In the congressional race, Republican Rep. Nick Begich, seeking a second term, advanced earlier to the general election along with independent Bill Hill. Democrats Jonathan Kreiss-Tomkins and Tom Begich, former state lawmakers, advanced in the race for governor, topping a field of mostly Republican candidates all vying to succeed Republican Gov. Mike Dunleavy. Tom Begich is Nick Begich’s uncle. Republican Bernadette Wilson also advanced on Tuesday.

The final places in the top four for the key races had not yet been settled by election night. The state accepts absentee and overseas ballots up to 10 days after the primary as long as they were postmarked by election day.

The incumbent Sullivan and Peltola are the leading candidates in the Senate race, after raising the most money and having statewide name recognition. It’s one of a handful of Senate races around the country considered competitive and pivotal for both parties’ hopes of controlling the chamber.

Dan J. Sullivan’s presence on the general election ballot adds a twist to the race because of Alaska’s ranked choice voting system. Under it, candidates who finish third or fourth in the general election can play a crucial role in deciding the eventual winner if their supporters rank other choices beyond them.

Becky Bohrer, The Associated Press