AP News Guide: Arizona, Utah, Idaho shape 2016 race

Even Trump, for all of his supreme confidence and frequent flights of hyperbole, is raising questions now about whether he can clinch the Republican nomination before the July convention.

[...] Clinton's lead in delegates is close to unassailable, but coming primaries may be friendly enough to rival Bernie Sanders to keep him credibly in the Democratic fight.

Will the deadly bombings in Brussels, tentatively tied to the Islamic State, nudge Republicans toward Trump, the man who wants to seal the borders to non-American Muslims?

Or toward a Washington insider steeped in foreign policy and national security experience?

The GOP race awards all 58 delegates to the winner.

If a Republican wins more than 50 percent support, he will take all 40 delegates; otherwise the prize will be proportional among Trump, Cruz and Kasich.

Trump's rallies were again raw, with obscenity-spitting protesters, angry supporters, bottles and insults thrown by demonstrators at the attendees and the kicking and punching of a protester by a man arrested at the scene.

Mitt Romney, the 2012 GOP nominee and a leading Trump critic, is using his influence with fellow Mormons and others in Utah to nudge voters toward Cruz, saying: "A vote for John Kasich is a vote for Donald Trump."

The ingredients were in a place for a good night for Sanders: thousands of supporters at a rally Monday, no campaign visits by Clinton, a caucus system that plays to his strengths, a largely white population and an election open to anyone, not just Democrats.

Trump won four of six races, taking all 99 delegates in Florida, scoring a strong victory in Illinois, edging out Cruz in North Carolina and taking the small prize in the Northern Mariana Islands.