Former presidential candidate Senator John McCain easily defeated an aggressive conservative challenger in a primary vote Tuesday despite a strong anti-incumbent mood, dpa reported.
The result means that McCain, 73, will again represent his Republican Party as a candidate for the Arizona senate seat.
The primaries, in which voters pick their party's candidates for November's congressional and gubernatorial elections, come amid an angry mood against politicians from both parties.
Voter anger over a still-sluggish US economy has also left President Barack Obama's Democrats fearful of losing their majorities in the Senate and House of Representatives.
Moderate politicians were seen as especially vulnerable as voters in both parties have turned increasingly partisan in the past few years.
McCain, the Republican Party's nominee in the 2008 presidential election, has spent over 20 million dollars in the battle to keep the Arizona Senate seat he has held for more than two decades.
He faced former congressman and talkshow host JD Hayworth, who questioned McCain's conservative credentials.
Once a self-styled "maverick" who worked with Democratic lawmakers on many signature issues over his tenure in the Senate, McCain moved to the right on hot-button topics such as immigration in a bid to fend off Hayworth's bid for the Republican nomination.
As polling stations closed US television projections gave McCain an easy win. In the early count published by the Arizona Secretary of State he enjoyed 59 per cent of the vote compared to his opponent's 30 per cent.