In Alaska, a contentious dispute has emerged over the candidacy of Dan J. Sullivan, who seeks a Senate seat under his legal name, directly challenging incumbent Republican Senator Dan S. Sullivan. The state’s election officials have questioned Dan J. Sullivan’s eligibility, sparking a political controversy with potential implications for control of the U.S. Senate.

Dan J. Sullivan, a former teacher from Petersburg, Alaska, filed to run for Senate in late May, shortly before the nonpartisan primary filing deadline. Alaska’s primary, set for Aug. 18, will advance the top four candidates to the November general election, which uses ranked-choice voting. Voters can rank multiple candidates, raising concerns that the presence of two similarly named contenders could cause confusion and affect the race outcome. Some Republicans worry that votes intended for Senator Dan S. Sullivan could be diverted to Dan J. Sullivan, potentially aiding the leading Democratic candidate, former Representative Mary Peltola.

On Monday, Lieutenant Governor Nancy Dahlstrom, a Republican, announced an investigation into allegations that Dan J. Sullivan had coordinated his candidacy with Peltola to disrupt the Republican vote. Carol Beecher, Alaska’s top elections official who operates under the lieutenant governor’s office, sent Dan J. Sullivan a letter demanding proof of his eligibility by Thursday night. The letter referenced suspicions about party affiliation timing, campaign similarities, and links to Amber Lee, a Democratic consultant previously associated with Peltola.

Dan J. Sullivan has denied any coordination with Peltola or her campaign. He confirmed that Lee is advising his campaign but contended that her involvement does not constitute grounds for an investigation. In communications with election officials, he stated he registered as a Republican after his prior affiliation with the Alaskan Independence Party ended, aligning himself with “compassionate conservatism.” He criticized the effort to remove him from the ballot, asserting that it appeared to serve the interests of the incumbent Senator rather than uphold fair election practices.

Republican operatives have pointed to Dan J. Sullivan’s past political donations, which include small contributions to Peltola’s campaigns and other Democrats, as evidence of potential strategic coordination. The National Republican Senatorial Committee (NRSC) has argued that Dan J. Sullivan’s candidacy could be a deliberate ploy by Democrats to split the Republican vote. In turn, Dan J. Sullivan insisted that the NRSC is free to oppose his candidacy politically but should not use state authority to exclude him from the ballot.

The Alaska Division of Elections’ inquiry has drawn scrutiny from civil liberties advocates. The American Civil Liberties Union of Alaska expressed concern about the state’s handling of the case, warning that disqualifying a qualified candidate without clear legal basis could undermine democratic norms.

The race has intensified given Alaska’s significance in the broader Senate contest. Democrats are aiming to flip multiple seats to gain control of the chamber, and Alaska is seen as a key battleground. Peltola, who has emphasized issues such as resource management and local values, remains well-funded and competitive in a state with a traditionally Republican leaning but reputation for political independence.

As the situation develops, the political and legal questions surrounding Dan J. Sullivan’s candidacy highlight the complexities of Alaska’s unique election system and the high stakes of closely observed Senate contests. Both the campaigns and election officials continue to navigate the situation as the primary approaches.