Republican frontrunner Donald Trump and Democratic favorite Hillary Clinton swept to victory in Arizona, one of three western states to hold contests on Tuesday.

The results saw Arizona award all its 58 Republican delegates to Trump in a winner-takes-all contest, and the majority of its 75 Democratic delegates to Clinton.

Clinton mentioned the attacks in Brussels during her victory speech, saying it was a "time for America to lead, not cower."

The result in Arizona pads Clinton's overall lead against her rival, Vermont Senator Bernie Sanders.

Sanders brushed off the defeat, saying at a campaign event in California that he had already won 10 primary elections and caucuses, and "unless I am mistaken we are going to win a couple more tonight."

In Utah, however, Sanders managed to clinch his first victory in the nominations race since March 8.

"Thank you to all those who caucused tonight in Utah!" he wrote on Twitter.

Within the hour, the self-proclaimed democratic socialist had also secured victory in Idaho, where 23 of the Democrats delegates were in play.

Utah looked to be a stumbling block for Trump, who was polling at just 11 percent in the state with 40 delegates up for grabs. Although he has managed to sway a number of religious voters, the state's 60.7% Mormon population largely dislikes the real estate mogul, perhaps in no small part to former presidential candidate and fellow church member Mitt Romney condeming the billionaire's candidacy in no uncertain terms.

ksb, es/jr (AP, AFP, Reuters)