Former Secretary of State Hillary Clinton and businessman Donald Trump — Democratic and Republican presidential front-runners, respectively — continue to face stiff challenges on the road to their parties' conventions.

Tuesday saw voters in three western states enter the fray.

Trump and Clinton were projected to win their parties' Arizona primaries by NBC News. Sen. Bernie Sanders of Vermont, meanwhile, was the projected winner in the Utah and Idaho Democratic caucuses. Ted Cruz was the projected winner of the GOP's Utah caucus, according to NBC.

Polls ahead of the contests indicated Trump was likely to win in Arizona, and Sen. Ted Cruz of Texas was the GOP favorite in Utah.

One key question for the evening is whether Cruz could capture 50 percent of the Utah vote over Trump and Ohio Gov. John Kasich, which would garner him all 40 of the state's delegates.