In a federal lawsuit filed on Thursday, the justice department said the inclusion of another Dan Sullivan on the ballot could lead some to mistakenly cast their vote for the wrong candidate.

Polls suggest the race between Sen Sullivan and Democrat Mary Peltola is tight, with Peltola holding a narrow lead in the final days before the 3 November midterm elections.

The government wants the judge to bar the state from certifying the results if Sen Sullivan loses by a margin less than the other Sullivan.

Previous efforts to remove the other Sullivan, a retired teacher, from the ballot have been rejected by the Alaska Supreme Court.

President Donald Trump has referred to the second Sullivan’s candidacy as a “scam” and said his administration was looking at “powerful legal options” to prevent him from running.

The senator will be listed on the ballot as the Republican incumbent, and Alaska’s ranked-choice voting system means that voters could select both if they are unsure at the ballot box.

In court documents, the justice department said Alaska “will fail in its obligation to protect the integrity of its elections” if it includes “any electoral results tainted by the inclusion on the ballot of Daniel J Sullivan”.