Dan J. Sullivan, a retired teacher who is challenging the Republican senator Dan S. Sullivan of Alaska, won a spot on the general-election ballot on Tuesday, according to The Associated Press.
His emergence from the state’s nonpartisan primary poses a headache for the incumbent.
Dan J. Sullivan is not expected to wage a competitive general-election campaign. But Republicans have worried for months that some voters may confuse the two Sullivans in November, potentially depriving Senator Sullivan of votes and lifting his well-funded Democratic challenger, former Representative Mary Peltola, to victory.
Senator Sullivan and Ms. Peltola easily earned spots on the general-election ballot; soon after polls closed a week ago, The Associated Press said they both had advanced. But Dan J. Sullivan won just a few thousand votes, and it took about a week for it to become clear that he had secured one of the four spots on the November ballot.
Democrats and Republicans alike see Dan J. Sullivan as no mere campaign curiosity. If he wins even a sliver of general-election votes, it could be decisive in a narrow race.
Alaska uses a ranked-choice general-election system, which means that voters confused about the Sullivans could simply rank them both before Ms. Peltola — but it is unclear how the dynamic may play out in voting booths.
Senator Sullivan trailed Ms. Peltola by nearly six percentage points in the nonpartisan primary.
It was unclear late Tuesday whether another Republican, Gerald L. Heikes, would join the Sullivans on the ballot in November, potentially offering Ms. Peltola another marginal lift.
The contest in Alaska is one of a handful of competitive races seen as the most likely to determine which party wins control of the Senate.
With Republicans now holding 53 seats, Democrats would have to keep all their seats and flip four to win the chamber in the midterms. Democratic leaders consider Alaska to be one of their most promising targets.
It was not always clear that Dan J. Sullivan, running as a Republican, would even be eligible.
The Alaska Division of Elections, which is overseen by the state’s Republican lieutenant governor, removed Dan J. Sullivan in June from the primary ballot, finding that his candidacy was intended to confuse voters and was not a “good-faith” effort. An Alaska judge, in turn, restored his spot on the ballot, saying that the elections agency had exceeded its authority.
Republicans have claimed that Ms. Peltola’s campaign planted Dan J. Sullivan in the race to trick voters. But the Peltola campaign has denied coordinating with him. He said in a recent interview that he had voted for Ms. Peltola in her bids for the House of Representatives in 2022 and 2024, but that he was running in good faith and was not a secret Democrat.
Broadly, Democrats in Alaska have dismissed allegations of foul play, casting Dan J. Sullivan’s candidacy as an amusing but far from unheard-of quirk of the insular world of Alaska politics.
When Senator Sullivan was first elected to the Senate in 2014, another Republican named Dan Sullivan, then the mayor of Anchorage, was also on the primary ballot as a candidate for lieutenant governor.
On the day of this year’s primary, the former mayor weighed in on the Senate race. “As the OG Dan Sullivan, I urge Alaskans to vote for Sen. Daniel S. Sullivan,” he said in a statement on social media. “He’s been great for Alaska.”
When Dan J. Sullivan announced in May that he was entering the race, he said in a statement, “It’s time for Alaska to elect a Sullivan that’s on their side.”
Kellen Browning contributed reporting.
