The U.S. Department of Justice has filed a lawsuit seeking to prevent Alaska from certifying its Senate election results if Republican incumbent Dan Sullivan narrowly loses, intensifying a legal battle ahead of the November 3 midterm elections.

The lawsuit, filed in federal court in Anchorage, centers on the presence of two Republican candidates with nearly identical names on the ballot: incumbent Dan S. Sullivan and challenger Dan J. Sullivan Jr. The Justice Department argues that the similar names could confuse voters and affect the election outcome.

Democrat Mary Peltola is also competing in the closely watched race, which could influence the balance of power in the U.S. Senate.

President Donald Trump said he supported the lawsuit and indicated that he had directed the Justice Department to pursue the action. The administration says the case is intended to protect election integrity.

However, election-law experts have questioned the legal basis for the preemptive challenge, raising concerns about the implications for state authority over elections and the certification process.

The case places Alaska’s Senate contest under additional scrutiny as both parties prepare for a consequential national vote. A court ruling could have implications for how election disputes are handled in other closely contested races.

The lawsuit remains a legal challenge, not a determination that the election has been compromised.