Democratic presidential candidate Hillary Clinton and Republican candidate Donald Trump won Tuesday's Arizona primary.
The Associated Press called both the winners at around 11:20 p.m. Eastern time.
Initial results which came in after the polls closed found Clinton receiving 61.1% of the vote, with Bernie Sanders at 36.4%.
On the Republican side, Trump was leading with 46.4% of the votes, followed by Ted Cruz with 20.7% and John Kasich with 10.4%.
Voting is also taking place in Utah and Idaho on Tuesday.
A poll released earlier on Tuesday in Utah shows Cruz winning the state with 53%, which would hand him all of the state’s 40 delegates. Trump, on the other hand, is barely in the double digits, coming in at a distant third with 11%.
The poll showed better things for Trump in Arizona, where he led the field with 38%, compared to 25% for Cruz and 14% for Kasich.
If the numbers hold true, the result in Arizona marks the latest victory for Trump, who last week won polls in Florida, Illinois, North Carolina and Missouri.
Trump's successes have resulted in some concerns among the Republicans, whose bigwigs met last week in order to lay out a plan to derail the frontrunner’s path to the nomination.
According to Politico, the meeting was organized by former Bush administration official Bill Wichterman, conservative activist Erick Erickson, and Bob Fischer, a prominent GOP fundraiser and bundler.
Aside from coordinating efforts to prevent Trump’s nomination, conservative activists and party leaders will also mull an option that was unthinkable just half a year ago: breaking with the Republican Party and launching an independent, third party bid for the White House.
Also last week, former Republican presidential candidate Mitt Romney said he would caucus for Cruz in Utah in an attempt to block Trump.