CLEVELAND – A horrific mass murder on the scale of the Orlando, Fla., nightclub massacre early Sunday would normally cause a time-out in a presidential campaign, as the candidates pause their attacks in deference to the dead and their families.

Donald Trump, though, was prompted by the deadliest mass shooting in American history to immediately launch into some of his harshest and angriest broadsides yet, demanding President Barack Obama resign, Hillary Clinton drop out of the presidential race, and that his call for a ban on Muslims entering the country be enforced.

As a result, the grieving and calls for healing on the campaign trail Monday were overshadowed by pitched political sparring over national security and gun control as Clinton and Trump respond to the latest act of terrorism on U.S. soil in prepared remarks Monday. Early Sunday morning, a gunman killed 49 people and wounded at least 53 in the Orlando nightclub before being killed in a shootout with police.

The rivals spoke about two hours apart on Monday afternoon - Clinton first, in Cleveland, and then Trump in Manchester, N.H., both in battleground states - laying out very different visions on the safety concerns that weigh heavily on voters, and particularly the swing voters who will decide the presidential contest.

Trump rose to the top of a crowded Republican field by pitching himself as an aggressive voice, pushing aside what he sees as a politically correct reaction of Clinton and Obama to the threat of immigration and terrorism, which he argues are closely related. Clinton has built her campaign around her deep well of experience and innate sense of caution and again made the case that Trump is a loose cannon prone to misfiring, creating an existential threat to the country at this dangerous time.

Both campaigns see the attacks as a key moment. For Trump, it underscores a climate of anger and fear that requires abandoning the old rules. For Clinton, it's a time to recognize the stakes of taking a gamble on a volatile personality.

Their reactions to the mass shooting highlight their disparate cases. Trump pounced on the tragedy on his Twitter account and in a statement, saying he predicted the attack while arguing that Clinton would bring in hundreds of thousands of refugees from the Middle East who pose imminent danger. He said "we can't afford to be politically correct anymore," asserting that it should be the litmus test for leading the country.

"In his remarks today, President Obama disgracefully refused to even say the words 'radical Islam'. For that reason alone, he should step down," Trump said. "If Hillary Clinton, after this attack, still cannot say the two words 'radical Islam' she should get out of this race for the presidency."

Clinton did, indeed, say the words "radical Islamism" on Monday, a rhetorical shift for her campaign and one the White House is refusing to make, amid concerns that the term needlessly complicates U.S. relationships with Islamic allies such as Saudi Arabia and underscores the misguided idea pushed by Islamic State and other extremists that the West is fighting a war against all of the world's 1.6 billion Muslims.

One word Clinton did not mention when she took the podium at a large industrial facility: Trump.

"Today is not a day for politics," Clinton said.

She delivered a speech much like the ones she gave following the shootings last fall in Paris and San Bernardino, in which she soberly laid out a plan for fighting Islamic State and sought to rally voters to embrace, not resist, diversity in these moments. As in the other addresses, she established her bona fides for confronting such threats with a multi-plank, deliberate plan focused on engaging U.S. allies, boosting the resources of local law enforcement to combat homegrown terrorism and toughening loose gun laws that allowed shooters to get the assault weapons used in their attacks.

"Whatever we learn about this killer and his motives in the days ahead, we know already the barbarity we face from radical jihadists is profound," Clinton said. "The attack in Orlando makes it even more clear we cannot contain this threat. We must defeat it."

Yet Clinton, without naming her rival, warned that the type of Muslim ban Trump has proposed is "is wrong. It is also dangerous. It plays right into the terrorists' hands." She reflected on 9/11 and how then-President George W. Bush stood firm against Americans inclined to take their anger out against Muslim residents.

Before Trump even spoke, he signaled he would be taking a much more direct approach in attacking Clinton. He said the attacks are a reflection of weak leaders and that "it is only going to get worse."

He boasted multiple times that he predicted an event like the one in Orlando was coming. "I'm getting thousands of letters and tweets that I was right about the whole situation," Trump said on Fox on Monday morning. He tweeted that he "called it and asked for the ban" on Muslim immigrants, though that assertion was at odds with the facts of the shooting; the gunman, Omar Mateen, was born in New York.

Clinton warned Monday morning on CNN said that Trump's rhetoric is "quite dangerous to our country." On NBC, she scoffed at his allegation that she won't brand the attack radical Islamic terrorism.

"Trump, as usual, is obsessed with name calling and from my perspective, it matters what we do, not what we say," she said. "It matters that we got (Osama) bin Laden, not what name we called him. But if he is somehow suggesting I don't call this for what it is, he hasn't been listening."

From the launch of his campaign, Trump has sought to harness voter anxieties about terrorism into anger and resentment of Washington. His call to ban Muslims is aimed to show he will take controversial steps to keep the U.S. secure. His proposed wall on the Mexican border is offered as a fortress against fear.

Clinton has warned repeatedly that Trump's strategy only emboldens the Islamic State and undermines the alliances crucial to confronting terrorism. She branded the Orlando attack at the gay club as an act of hate against the LGBT community and called on Americans to change gun laws, an issue that has grown increasingly important to Democrats in the age of mass shootings.

Monday had already been set as the unofficial start of the general election for the two presumptive nominees, with both candidates planning major speeches. Clinton had been expected to talk about unity; Trump had announced a broadside attack on Bill and Hillary Clinton's long record in public life.

"I had intended to come to Cleveland under very different circumstances," Clinton said, after being introduced by Ohio Sen. Sherrod Brown, a liberal Democrat often mentioned as a possible vice-presidential pick.

Still, it wasn't completely business as usual. Clinton canceled a rally with Obama that had been scheduled for Wednesday in Wisconsin, as well as two Ohio fundraisers scheduled for Monday. Trump canceled a second campaign stop in New Hampshire that was set for Monday afternoon.