In legal papers filed Friday, Brett Johnson, who is leading the legal team, acknowledged that vacancies in the U.S. Senate must be filled by a special election. But Johnson told U.S. District Court Judge Diane Humetewa that the U.S. Constitution allows the Legislature to let Ducey name a senator to serve until the next regular election.

2018 has been an exciting year from the start. As it comes to a close we’re looking back on some of the standout moments.

Martha McSally scored the political redo of a lifetime when she was appointed to the U.S. Senate on December 18.

Sen.-elect Kyrsten Sinema will be sworn into office before Martha McSally, who Gov. Doug Ducey appointed Tuesday to fill Arizona’s U.S. Senate vacancy.

Gov. Doug Ducey has appointed Martha McSally to fill the U.S. Senate seat that Sen. Jon Kyl will vacate at the end of the year.

The former leader of Arizona’s Libertarian Party filed a lawsuit against Gov. Doug Ducey Wednesday, arguing he must immediately hold a special election to fill the U.S. Senate seat formerly held by John McCain.

Supreme Court Justice Clint Bolick urged Gov. Doug Ducey to name Maricopa County Attorney Bill Montgomery to the U.S. Senate just days after John McCain died.

Two-time U.S. Senate candidate Kelli Ward said Monday she'll seek the top post in the Arizona Republican Party and likely forego any effort to seek the late Sen. John McCain's seat in 2020.

Adams, who served through Ducey’s first term, announced on Twitter that he will return to the private sector, although he did not specify his plans.

Congressman Ruben Gallego is considering a run for the United States Senate in 2020, when a special election will be held for the final two years of the late Sen. John McCain’s term.