Insurgent challengers fell flat in Florida on Tuesday as Republican U.S. Senator Marco Rubio won his party's nomination to seek re-election in November and U.S. Representative Debbie Wasserman Schultz held a big lead in her Democratic nominating race.

The non-traditional campaigns of Republican presidential nominee Donald Trump and U.S. Senator Bernie Sanders, who exceeded expectations in his failed Democratic White House bid, gave rise to speculation other insurgent politicians could gain traction this year.

But that was not the case, at least in closely watched nominating races in Florida.

Rubio, who abandoned his presidential campaign in March, cleared the initial hurdle in his battle for a second six-year term in the U.S. Senate. He defeated novice politician Carlos Beruff, a millionaire homebuilder, who embraced Trump.

U.S. Representative Patrick Murphy, a Democrat, won his party's Senate nomination on Tuesday and is expected to give Rubio a spirited challenge in the autumn campaign.

But Rubio might still harbor presidential ambitions. There were media reports this week that he had refused to commit to serving all six years of a Senate term if he were re-elected in November.

In early results on Tuesday night, Wasserman Schultz was leading law professor Tim Canova, an outspoken Wall Street critic aligned with Sanders.

In July, Wasserman Schultz resigned as head of the Democratic National Committee after emails were leaked suggesting members of the DNC favored former Secretary of State Hillary Clinton over Sanders instead of maintaining a neutral role in the presidential nominating race.

The episode helped fuel Canova's campaign, which also got a boost from Sanders' former supporters.

MCCAIN FACES CHALLENGE

Another big-name politician, U.S. Senator John McCain, was being challenged by a Tea Party conservative in Arizona's Republican nominating vote.

Results were expected later on Tuesday in McCain's race against former Arizona state Senator Kelli Ward, who, like Beruff, has embraced Trump.

Trump, who faces Clinton in the Nov. 8 presidential election, has endorsed both McCain and Rubio in their re-election bids even though he has rocky relations with both.

Trump offended McCain and many other Republicans last year by suggesting the maverick senator and party's 2008 presidential nominee was anything but a war hero because he was captured during the Vietnam War after his airplane was shot down during a bombing mission.

In March, Trump ended Rubio's presidential run by trouncing him in the Florida primary to cap a race in which the New York businessman taunted the first-term senator as "little Marco."

Rubio fired back, insulting Trump on everything from his hair color and the size of his hands to misspelled words in tweets.

During their re-election efforts, both McCain and Rubio have offered support for Trump as the party's White House nominee. But they have tiptoed around him, mainly out of concern that his provocative comments on illegal immigration, Muslims and U.S. support for NATO could alienate moderate and independent voters in their states.

At the same time, they have steered clear of attacks on Trump that might antagonize his core supporters.

Adding to the intrigue is that the fates of the two senators will likely play a big role in whether Republicans can upset expectations and maintain majority control of the Senate after November's election.

McCain was leading Ward by 55 percent to 29 percent in a CNN opinion poll released last week. But in the run-up to Tuesday's voting, Ward ratcheted up her attacks, arguing: "It's time to defeat the establishment and retire McCain," who turned 80 on Monday.

In trying to neutralize Ward's appeal with conservatives, McCain has touted his support for gun rights, his vow to cut government waste and endorsements from anti-abortion leaders.

If McCain, who chairs the Senate Armed Services Committee, wins on Tuesday, he would face Democratic U.S. Representative Ann Kirkpatrick.