While McSally, a two-term congresswoman and former combat fighter pilot, had the strongest resume, she failed in this regard. Polling indicates that Sinema, a moderate Democrat in a heavily Republican state, is the Democrats' best shot at winning a new seat in the Senate.
McCain and Arizona's junior US senator, Republican Jeff Flake, who is retiring at the end of this year, were both outspoken critics of President Donald Trump, a dynamic that put Arizona at the forefront of deep divisions within the Republican Party. Jeff Flake on the ballot Tuesday, both the late senator and President Trump - who did little to hide his disdain for McCain - have factored into the bitter primary there.
All three Republicans had distanced themselves from McCain, who frequently feuded with Trump, and Ward suggested that his family's announcement on Friday that he was stopping medical treatment was timed to hurt her campaign. That means McSally could come out on top even if a majority of Republicans split their vote between the more right-leaning Ward and Arpaio.
Graham, who was considered a centrist, was viewed as a more attractive general election candidate in the purple state.
Businesswoman Barbara Barrett, 67, is a former USA ambassador to Finland who unsuccessfully ran for Arizona governor in 1994 as the first Republican woman to seek that office.
Without wasting much time, Flake replied to Trump on Twitter, saying his claim about an attempted endorsement was false. Republican Gov. Doug Ducey could also be vulnerable this fall.
The following is a list of the some of the names most frequently mentioned as possible appointees to succeed McCain, according to Republican political consultants and various media outlets, including the state's leading newspaper, the Arizona Republic.
In Florida's 16th and 18th districts, lawyer David Shapiro and former Obama administration official Lauren Baer won their Democratic primaries to face incumbent Republicans in districts Trump won in 2016 but that Democrats hope will become competitive this year. Will it be south Florida Democrats or panhandle Republicans who turn out in numbers closer to presidential year voting?
The nation's eyes are on Arizona and its hotly contested U.S. Senate race, seen as a prime pickup opportunity for Democrats fighting to retake control of the chamber and challenge President Donald Trump's agenda on everything from illegal immigration to taxes and trade. It sets up the two states as key tests of the national political environment in November's midterm elections.
Dr Hilal Tipirneni, an Indian-American Democrat who sailed through her primary for a Congressional district unopposed, told The Straits Times: "The base is very energised". On the Democratic side, Former Rep. Gwen Graham and Philip Levine, the former mayor of Miami Beach, look to be the front runners for the Democratic nomination.
Former Oklahoma City Mayor Mick Cornett and mortgage company executive Kevin Stitt will go against each other in the GOP gubernatorial runoff.