Republican US presidential candidate Donald Trump addresses the American Israel Public Affairs Committee (AIPAC) afternoon general session in Washington March 21, 2016.[Photo/Agencies]

Trump's hardline immigration message is popular in Arizona, one of the US states that borders Mexico, and he leads in polls. He lags behind top rival Cruz in Utah.

Arizona will award its entire slate of 58 delegates to Trump.

In Utah, the state's 40 delegates will be awarded proportionate to the popular vote, unless a single candidate captures at least 50 percent of the vote, in which case that person will be awarded all the delegates.

On Monday, Trump warned against efforts to deny him the nomination if he falls short of securing the 1,237 delegates needed ahead of the July convention. Trump now has 678 delegates.

"I think it is going to be very hard for them to do," Trump said on CNN of any effort to deny him the nomination if he falls short. "I have millions of votes more than anybody."

Clinton showed her strength yet again in Arizona and looked to have a solid path to the Democratic presidential nomination. The two nominees from each party will meet in the Nov. 8 presidential election.

Sanders is looking for wins in many of the six Democratic contests this week. Alaska, Hawaii and Washington will vote on Saturday. Clinton will keep adding to her delegate total even if she is not the winner in a given state because Democratic delegates are awarded proportionally in all states.

Tuesday's Republican contests were the first since US Senator Marco Rubio of Florida dropped out a week ago after Trump drubbed him in his home state.

Kasich is the only other candidate still in the race, splitting the anti-Trump vote with Cruz.

In Arizona, Trump had the backing of former Republican Governor Jan Brewer and Maricopa County Sheriff Joe Arpaio, two of the most prominent supporters of a crackdown on illegal immigrants.