BY CAROLINE VAKIL – 06/20/23 Republicans are facing a dwindling number of alternatives to mount a challenge to Kari Lake in the Arizona Senate primary, raising concerns for the party over what should be a prime pickup opportunity next year. Lake, who narrowly lost her gubernatorial election to Gov. Katie Hobbs (D) last November, is weighing a potential Senate run for Sen. Kyrsten Sinema’s (I) seat. Rep. Ruben Gallego (D) has already thrown his hat in the ring, while Sinema has…