Mary Peltola, the Democratic candidate for Senate in Alaska, has shaken up her campaign in the final days before a high-profile primary, jettisoning at least one longtime senior aide and switching campaign managers. Two veteran contractors for Ms. Peltola’s campaigns were also let go.

Ms. Peltola, a former congresswoman who represents the Democratic Party’s best chance of flipping a crucial Alaska Senate seat, had enjoyed early momentum since announcing her bid in January, raising a significant amount of money and mounting a strong challenge to Senator Dan Sullivan, the incumbent Republican. But the days before Tuesday’s nonpartisan top-four contest have been shakier for her campaign.

She drew headlines by distancing herself from former Vice President Kamala Harris, who signed a fund-raising appeal from her PAC last week, asking donors to contribute to Ms. Peltola’s campaign. Running in a conservative state that is skeptical of national Democrats, Ms. Peltola kept Ms. Harris at arm’s length as Republicans eagerly jumped on the connection.

Last week, Ms. Peltola fired Elisa Rios, a close adviser who had helped run her two campaigns for the House and was campaign manager for her Senate bid, according to a person familiar with the move. She also fired a deputy campaign manager. The moves came before the dust-up involving Ms. Harris.

Anton McParland, another top Peltola confidant who served as her chief of staff in Congress and was running her campaign alongside Ms. Rios, “has transitioned into a new role” as a general consultant, Ms. Peltola’s campaign said.

The campaign declined to comment on the reason for the shake-up or for Mr. McParland’s new role, and also declined to make him available for comment. Ms. Peltola herself did not respond to requests for comment.

Harry Child, a spokesman for Ms. Peltola, said in a statement that “the campaign has undergone staffing updates as we transition into the general election and we appreciate the contributions of everyone who built the winning campaign to send Mary to the U.S. Senate this November.”

The campaign said that Cheryl Bruce, who had been serving as deputy campaign manager, was now Ms. Peltola’s campaign manager. And it said the contractors who were let go had been part-time workers whose services weren’t needed for the general election.

Ms. Peltola’s allies emphasized that the candidate remained in a strong position, pointing to a new poll from Data for Progress on Monday suggesting she had a lead over Mr. Sullivan.

But Republicans pounced on the news.

“Even Mary Peltola’s closest advisers know her ‘Alaska last’ campaign is a lost cause,” Nick Puglia, a spokesman for the National Republican Senatorial Committee, said in a statement.