That puts Trump at 741 delegates, compared to 421 for his main rival Cruz and 145 for Kasich, according to a CNN tally.
Democrats award their delegates proportionally, with Clinton due to take the lion’s share in Arizona.
The deadly attacks in Brussels changed the tone of voting day from the start, with Trump and his main rival Cruz seizing the moment to bash President Barack Obama’s foreign policy — and tout their own tough stances on immigration.
Anyone who tries to attack the United States will “suffer greatly,” Trump said, in typically blunt tones that have shaped his populist run for the White House, propelling him from outsider to firm favorite for the Republican ticket.
“Belgium is a horror show right now. Terrible things are happening,” he said. He also told CNN that Belgian authorities could have thwarted Tuesday’s attacks if they had used torture against a terror suspect who was captured days earlier.
Cruz used similarly strong language, calling for US law enforcement to be empowered to “patrol and secure Muslim neighborhoods before they become radicalized.”
Clinton thanked Arizona for her victory during a Tuesday night speech in Seattle. But she also forcefully denounced her Republican rivals for their strident talk about how they would respond to the Brussels attacks.
“What Donald Trump, Ted Cruz and others are suggesting is not only wrong, it’s dangerous. It will not keep us safe,” she said.
“We need a president who can provide leadership that’s strong, smart, and steady,” she added. “The last thing we need are leaders who incite more fear.”