Donald Trump said he ordered the justice department to file a lawsuit to block the certification of Alaska’s US Senate results if the Republican incumbent on the ballot does not win.

“I’m the one that said do it,” Trump told reporters on Friday.

The justice department claimed there could be “voter confusion” about the two Republican candidates on the ballot named Dan Sullivan, which it claims might influence the race’s outcome in favor of the Democratic nominee, Mary Peltola.

Alaska could determine control of the Senate, and polls suggest the Republican incumbent senator, Dan S Sullivan, is in a dead heat with Peltola, a former Democratic congresswoman. Another candidate named Daniel J Sullivan, a retired schoolteacher, is also running as a Republican and will appear on the November general election ballot.

The administration is asking for there to be a pause in certifying the vote in Alaska “pending an investigation” to determine whether votes that are cast for Dan J Sullivan were actually meant to be for the Republican incumbent.

The federal government argues in the complaint that “the sole purpose” of Dan J Sullivan’s of candidacy is to “benefit the Peltola campaign by reducing the number of votes for Senator Sullivan”.

As a result, “there is a substantial likelihood that a certification of the election will reflect an electoral process that lacked integrity”, it writes.

The state uses a ranked-choice voting system in their elections, under which the top four candidates from an open primary advance to the general election. Voters then rank candidates in order of preference, and votes can transfer to their next-ranked candidate as lower-placed contenders are eliminated.

The president and his allies have repeatedly claimed, without evidence, that Daniel J Sullivan – who is challenging the two-term incumbent – is an “impostor”.

Meanwhile, many Republicans across the country have accused the former teacher, who lives in Petersburg – a town of about 3,000 people in the southern part of Alaska – of being a Democratic plant in place to cannibalize votes from the Dan S Sullivan.

Trump has routinely disparaged the state’s voting system, adopted by voters in 2020, calling it a “scam” and encouraging Alaskans to support a state ballot measure to repeal it. The incumbent senator will appear on the 3 November ballot in Alaska with the words “(Registered Republican) Incumbent” next to his name to make it clearer for voters.

Voting rights experts say the basis for the lawsuit is thin given the fact that any meaningful investigation into voters’ preferences after they have voted would be practically impossible to conduct.

In June, the Alaska supreme court ruled that the Dan J Sullivan could remain on the ballot, despite the frustration it has caused the Trump administration and national Republicans hoping that the incumbent Sullivan can win against Peltola, a moderate Democrat, in their bitter fight for a Senate seat that could deliver Democrats a key victory in their path for control of the upper chamber of Congress.

The Trump administration’s targeting of Alaska’s Senate race is particularly consequential as Democrats have been making waves in flipping the red-leaning state.

Alaska’s Democrats believe circumstances have aligned for them to win a slew of competitive elections in the midterms, with the Senate seat being a top prize. If Peltola were to win the election next month, she would be the first Democrat to win the seat in nearly two decades.