WASHINGTON — President Donald Trump might want to be careful about challenging Joe Biden to come out and fight.

For months, he has slammed Biden, the Democratic presidential nominee, for staying in the “basement” instead of campaigning.

On Monday, Biden traveled to Pittsburgh, a Democratic hub in a pivotal swing state, to try to turn Trump’s fear-based case for re-election on its head. Looking lively and speaking forcefully, he condemned unwarranted police violence, rioting and looting, and militia activity. Then he laid the blame for all of it at Trump’s feet.

“The fires are burning,” Biden said, “and we have a president who fans the flames rather than fighting them.”

And responding to Trump’s formulation that no one would be safe in “Biden’s America,” he said, “These are not images from some imagined ‘Joe Biden’s America’ in the future — these are images from Donald Trump’s America today.”

Trump and his campaign were left at odds with each other in responding to Biden, and the White House seemed to shift its stance Monday on whether increased violence is a political gift to the president.

The fight over whether Americans are in more peril now and in the future under Trump or down the road under Biden has become a central issue a little more than two months before Election Day. Many Democrats were heartened by Biden’s remarks.

Some had urged him publicly and privately to hit the campaign trail, hammer Trump and forcefully denounce criminal activity that has coincided with protests against racial injustice. Biden appeared to accomplish all three of those goals Monday, pushing back hard against several of the president’s main attacks.

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Kristen Hawn, a veteran Democratic strategist who advises members of the House’s moderate Blue Dog Coalition, said: “President Trump sees all of this terrible violence and unrest, and rather than attempt to heal and bring people together, he sees nothing more than a political opportunity to revive his struggling campaign. Biden did exactly what a president should do — condemn the violence in a way that doesn’t stoke the fire and put more people in danger.”

Biden said that Trump isn’t looking for a solution and that his record is that of presiding over more deaths from the coronavirus than in all the wars America has fought since Korea, as well as more job losses than at any other time since the Great Depression.

“The simple truth is Donald Trump failed to protect America,” he said. “So now, he’s trying to scare America.”

Fear is Trump’s go-to campaign tool, and he’s had a mixed record with it. In 2016, he warned voters that a Hillary Clinton presidency would mean endless investigations and globalism, and he won. But in the 2018 midterm elections, his talk of immigrant caravans and the possibility of a divisive impeachment fight didn’t save the House Republican majority.

White House press secretary Kayleigh McEnany said Monday that Trump wasn’t relying on violence to win re-election.

“He’s not rooting for more violence in the slightest,” she said shortly before Biden spoke.

That was a shift from last week, when Trump counselor Kellyanne Conway suggested that disorder benefits the president politically.

“The more chaos and anarchy and vandalism and violence reigns, the better it is for the very clear choice on who’s best on public safety and law and order,” Conway said on Fox News.

One measure of Biden’s effectiveness Monday is that he appeared to throw Trump and his campaign for a loop when he called for the prosecution of criminals, just days after a Republican convention in which the president and his surrogates looked to build a case that Biden espoused “socialist” values permissive of lawlessness.

“I want to be clear about this: Rioting is not protesting. Looting is not protesting. Setting fires is not protesting,” Biden said. “Those who do it should be prosecuted. Violence will not bring change, only destruction. It’s wrong in every way. It divides instead of unites.”

In an official statement released just after Biden had condemned burning, looting and rioting, the Trump campaign accused him of failing to “condemn the left-wing mobs burning, looting and terrorizing American cities.”

In a tweet, Trump disagreed with his campaign’s conclusion that Biden hadn’t criticized criminals at all.

“Just watched what Biden had to say,” Trump wrote. “To me, he’s blaming the Police far more than he’s blaming the Rioters, Anarchists, Agitators, and Looters, which he could never blame or he would lose the Radical Left Bernie supports!”

That wasn’t true, either, although it was closer to reality. Biden had lamented “unwarranted police shootings” and “excessive force,” but he also talked about working with law enforcement and protesters to find common ground.

“I believe I can bring those fighting for racial justice to the table,” he said. “I know most cops are good and decent people. I know the risk they take every day with their lives. And I am confident I can bring the police to the table.”