While the first Republican presidential primaries are nearly a year away, a shadow contest of another sort is underway with several Republicans, including one in Arizona, openly jockeying to position themselves as potential running mates to Donald Trump, the early front-runner for the nomination.

Democrat Ruben Gallego held the first public events of his U.S. Senate campaign Saturday, taking aim at independent incumbent Kyrsten Sinema and casting his candidacy in a patriotic appeal to the American dream.

Politicos say that the possibility of a three-way election serves Republicans better than Democrats in light of Sen. Kyrsten Sinema’s switch to independent.