Democratic Senate candidate Mary Peltola has denied she knew anything about an alleged “scheme” that led to two men named Dan Sullivan standing in the Alaska Senate race.

The denial comes as the Trump administration continues to escalate a criminal investigation into the matter, according to US media. The Republican governor of the state ordered an official inquiry earlier this week.

Dan S Sullivan, the incumbent Republican senator running for re-election, and allies have accused the Democrats of trying to confuse voters.

The Alaska race is considered by analysts to be one of the tightest of the upcoming US midterm elections, which will decide which party controls Congress.

“I just want to clear the air,” Peltola said while speaking to voters on Thursday. “I knew nothing about any other candidate on the ballot except for me and the incumbent. That is all I have ever known about. I am not interested in tricking voters.”

Both Dan Sullivans have been running for the open Senate seat for some time. Still, controversy erupted earlier this week when The New York Times, external reported that Peltola’s team worked with people who tried to recruit spoiler candidates in the Senate race.

The Times’s report alleged that people connected to Peltola’s campaign, as well as senior aides at the Democratic Senatorial Campaign Committee (DSCC), worked to try to recruit Dan J Sullivan, a retired teacher who lives in a remote fishing village, to stand in the Senate race.

The paper said it had seen text messages and interviewed 12 people who participated in or were told of the plan, or were would-be candidates who the team tried to recruit. The BBC has not independently verified the reporting.

The Peltola campaign has denied those reports and Sullivan has denied any links to the campaign.

But those denials have not stopped the US Department of Justice and Republicans from attacking Peltola.

The justice department has begun issuing subpoenas targeting Democratic officials allegedly connected to the effort to recruit Dan J Sullivan to be on the Alaska ballot, according to CBS News, the BBC’s US news partner.

No charges have been filed as of Friday morning.

The Trump administration filed a federal lawsuit last week aimed at preventing the certification of the result if the Trump-backed Sullivan loses, arguing that the presence of both of them on the ballot could confuse voters.

On Wednesday, the justice department amended its lawsuit to include the reporting by the Times, citing significant sections of the story as well as Governor Mike Dunleavy’s announcement of an investigation.

The legal action comes days before voters across the US head to the polls. This race in Alaska is among the closest-watched in the country, as it could be the deciding factor in who controls the Senate.

The non-partisan Cook Political Report currently classifies the race as a toss-up.