The FBI has begun reaching out to donors of Dan Sullivan asking about potential deception, as federal authorities ramped up their investigation of the US Senate candidate in Alaska who shares a name with the Republican incumbent.

Agents have contacted donors in at least two remote communities in Alaska and a couple in Massachusetts.

An Anchorage-based FBI agent visited a boat dealership in Petersburg, a small fishing community accessible only by air or water where the candidate lives.

The agent left a business card for Charles Flint, who told the Associated Press he has known Dan Sullivan for years as a respected teacher and musician.

The FBI visits came after federal officials confirmed the existence of a criminal probe over the candidate. The US Department of Justice also pushed Friday for a court order to isolate certain Alaska ballots to investigate potential voter confusion.

Flint contributed $500 over the summer to what he considered a long-shot campaign, saying he knew Dan Sullivan would have expenses and respected him for “throwing his hat in the ring.”

Flint said the FBI agent asked his son, who works at the dealership, whether Flint felt he had been “misled” about which candidate he was supporting.

“I don’t feel like I’ve been misled at all,” Flint, who has been out of town, told the AP in a telephone interview, adding he had no intention of calling the agent but would “let him waste his time trying to track me down.”

“I don’t think there’s any confusion,” he said, adding he intends to rank Democrat Mary Peltola first on his ballot, followed by Dan Sullivan. “Everybody knows who the incumbent is.”

President Trump was asked about the case on Saturday night, during a Halloween party at his Mar-a-Lago estate, and called it “voter fraud at the highest level.”

He also suggested that Dan Sullivan had gone into hiding: “Nobody can find him now, so he knows he’s guilty.”

The president also suggested, without providing details, that top Democratic leaders outside the state could have been involved, and that they should be prosecuted.

Alaska US Attorney Michael Heyman told reporters in Anchorage the federal investigation has been ongoing for several months, but recent revelations from The New York Times that Peltola’s campaign appeared to be involved in recruiting retired teacher Dan Sullivan have resulted in a “significant surge of law enforcement assets to Alaska.”

Two different FBI agents were dispatched to Sitka to conduct a brief interview at the doorstep of another donor.

That donor, who asked that their name not be published given the ongoing investigation, said the agents asked whether the contribution had been made to the Sullivan the donor intended.

The conversation lasted about five minutes, the donor told the AP.

The donor said the agents were “scrupulously polite” and emphasized that the conversation was entirely voluntary.

Yet another donor, Pat Campbell, of Groton, Massachusetts, said a couple of FBI agents came to her door Friday and spoke with her husband.

“They said they were from the FBI and investigating fraud in election contributions,” Campbell wrote in a text message to AP. “No, we had not been defrauded. We knew to whom we had contributed.”

The developments come just days before Tuesday’s ranked choice general election in a potentially pivotal race in which Peltola, a former congresswoman, is challenging Republican Sen. Dan Sullivan.

At a campaign rally in Anchorage on Friday, Peltola again denied involvement in any plan to place candidates on the ballot to detract from the incumbent senator.

She said she was “deeply offended” by the allegations, which she called “garbage” and part of a “smear campaign” to suppress turnout on the eve of the election.

“I know I can beat Dan Sullivan. I do not need any help winning this race,” she told a small group of campaign volunteers at an Anchorage aviation museum.