WASHINGTON — Voters weighed the merits of establishment candidates against outsiders, as U.S. Sen. John McCain, the 2008 Republican presidential nominee who took a hard turn to the right in a bid for a fifth Senate term, handily defeated a conservative talk radio personality.

The Arizona election was one of five state primaries Tuesday in which voters chose party candidates for November balloting nationwide that could end Democrats' majority hold on the House of Representatives and, perhaps, the Senate.

The 73-year-old McCain now begins a final 10-week push and will be the heavy favourite. Former Tucson councilman Rodney Glassman won the Democratic nomination but he faces an uphill fight in heavily conservative Arizona.

The primary season has tested the strength of insurgent campaigns. With Americans in a sour mood over the down economy and unemployment at nearly 10 per cent, outsiders -- especially those aligned with or belonging to the amorphous, hard right tea party movement -- already have swept away some incumbents.

McCain, however, went into the vote with a healthy lead in the polls over tea-party-backed former Rep. J.D. Hayworth.

The challenge from party's right wing prompted McCain, who has a long history of bucking the conservative establishment, to toss aside his self-described "maverick" label. He adopted a hard-line stand on immigration just a few years after working with Democrats on a path to citizenship for those in the country illegally. "Complete the danged fence," he says in a campaign ad, three years after dismissing the effectiveness of building a fence on the U.S.-Mexico border.

McCain's 2008 running mate, former Alaska Gov. Sarah Palin, was trying to help a tea party-backed candidate in her home state.

Joe Miller's upstart Republican primary bid against Sen. Lisa Murkowski -- who hoped voters would reward political experience -- looked like a long shot. But Murkowski was in a surprisingly close race with about a third of the vote counted.

"He's got the backbone to confront Obama's radical agenda," Palin said of Miller in a recorded call to voters.

Palin has become a de facto leader of the ultraconservative tea party movement in its bid to unseat incumbents. However, she endorsed McCain, who elevated her to the national stage by making her his surprise vice-presidential pick two years ago.

In previous primaries this year, voters have shown both a readiness to fire veteran lawmakers and a willingness to keep them.

The tea party has had mixed success. It won big in Nevada, Kentucky, Colorado and Utah Republican Senate contests but lost just about everywhere else.

But no matter Tuesday's outcomes, there's no question that the tea party and Palin have provided an enormous dose of enthusiasm for Republicans heading into the fall campaign. And that's dangerous for a dispirited Democratic base.

In Vermont, Democratic Sen. Patrick Leahy, first elected in 1974, coasted to renomination for what is likely to be a new term in November. A five-way Democratic primary for Vermont governor was too close to call; the victor could win the seat currently held by a Republican.

Also, Arizona Gov. Jan Brewer, the Republican who signed the tough law designed to crack down on illegal immigration, cruised to nomination for a new term.

The race for an open Arizona seat in the House, vacated by retiring Republican Rep. John Shadegg, drew 10 party hopefuls, including Ben Quayle, son of former Vice-President Dan Quayle.

Quayle drew much attention to his campaign when he called Obama the worst president in American history. It also was disclosed that he once wrote for an adult Web site, tarnishing his attempts to align himself with Republican family values campaigns.

In Florida, former health care executive and political novice Rick Scott pushed past state Attorney General Bill McCollum to win Florida's Republican gubernatorial primary. McCollum had said voters have not been swayed by his opponent's outlay of $39 million of his own money to blanket the state with commercials, most attacking McCollum.

Scott faces Florida chief financial officer Alex Sink, who won her Democratic primary.

Washington-backed Rep. Kendrick Meek beat billionaire and real estate businessman Jeff Greene, who has spent lavishly from his fortune and forced Meek to drain his campaign coffers.

Meek will face Republican Marco Rubio and Gov. Charlie Crist, the Republican who turned independent in face of the Rubio tea party juggernaut.