Since writing “HAPPY MOTHER’S DAY” at 8:10 a.m. on Sunday, Trump has used his Twitter account to make or elevate allegations of criminal conduct against no less than 20 individuals and organizations. Since Sunday, he has tweeted more often about alleged crimes by his opponents than he has about the pandemic ravaging the country with mass death and unemployment.

The list of purported culprits Trump has charged include two television news hosts, a comedian, at least five former officials from the FBI and Justice Department, the state of California, a broadcast television station and at least five top national security officials from President Barack Obama’s administration.

Trump tweeted multiple times about alleged criminal activity against him by Obama but struggled to elaborate beyond his frequent references to “Obamagate.”

“And if you look at what’s gone on, and if you look at, now, all of this information that’s being released,” Trump said during a Rose Garden news conference Monday. “And from what I understand, that’s only the beginning — some terrible things happened, and it should never be allowed to happen in our country again.”

Pressed for specifics by a Washington Post reporter, Trump demurred.

“You know what the crime is. The crime is very obvious to everybody,” he said. “All you have to do is read the newspapers, except yours.”

Over the course of his presidency, Trump has responded to criticism of his performance or comments by suggesting or outright asserting that his critics are criminals. Trump, who campaigned for the White House by leading “Lock her up!” chants against his Democratic rival, is now reverting to a familiar political tactic as he faces the most significant challenge of his presidency, said Russell Riley, a presidential historian at the University of Virginia’s Miller Center.

“He’s using this as a means of distraction,” he said. “As we’ve seen over the years, when the pressure on him gets turned up, there’s an attempt to deflect attention onto his political opponents.”

The president, who has developed a habit of watching copious amounts of cable news coverage at all hours of the day, lashed out against MSNBC anchor Joe Scarborough on Tuesday, insinuating that he should be prosecuted for murder.

“When will they open a Cold Case on the Psycho Joe Scarborough matter in Florida. Did he get away with murder?” Trump wrote on Twitter at 6:54 a.m. “Some people think so. Why did he leave Congress so quietly and quickly? Isn’t it obvious? What’s happening now? A total nut job!”

Trump’s conspiratorial claim that Scarborough murdered a congressional aide who died in 2001 has been debunked by The Post and other media outlets. But the president has expressed his frustration with Scarborough’s “Morning Joe” show and its critical coverage by repeatedly floating the murder accusation. Scarborough, a contributing opinion columnist at The Washington Post, responded to Trump’s tweet on air, encouraging the president to “turn off the television” and renew his focus on the deadly pandemic.

The White House did not respond to requests for comment about Trump’s claims that his political opponents are criminals.

“The other side is where there are crimes,” Trump said on April 9 2018, the day news broke that the office of his personal lawyer, Michael Cohen, had been raided by the FBI. Cohen later pleaded guilty to several felonies including campaign finance violations, implicating Trump.

Trump responded by insinuating that investigators should prosecute Cohen’s father-in-law, though he did not identify any crime.

Since taking office, Trump has casually accused multiple people of treason, ranging from former FBI Director James B. Comey to the American media. He has regularly accused people of perjury or mishandling classified information, usually without evidence. He has said former Secretary of State John F. Kerry “should be prosecuted” for an alleged violation of the Logan Act, a rarely invoked law preventing private citizens from conducting diplomacy on behalf of the U.S. government, due to his interactions with Iranian officials. Kerry has called Trump’s allegation “another presidential lie.”

When House Speaker Nancy Pelosi (D-Calif.) ripped up Trump’s State of the Union speech in February, Trump said the act of defiance was criminal in nature.

“First of all, it’s an official document, you’re not allowed, it’s illegal what she did,” Trump said. “She broke the law.”

When House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) read an embellished version of a phone call between Trump and Ukrainian President Volodymyr Zelensky during a congressional hearing in September, Trump suggested he should be arrested.

“Why isn’t Congressman Adam B. Schiff being brought up on charges for fraudulently making up a statement and reading it to Congress as if this statement, which was very dishonest and bad for me, was directly made by the President of the United States? This should never be allowed!,” the president wrote.

While most of Trump’s accusations are not grounded in truth, they are regularly adopted in a conservative media ecosystem that has formed a symbiotic relationship with the president, said Nicole Hemmer, a scholar at Columbia University and author of “Messengers of the Right,” about right-wing media.

That relationship — in which Trump uses his platform to amplify voices that had previously been relegated to the fringe of public discourse — has been beneficial to the president as he has faced his own set of criminal accusations, she said.

By elevating counter-allegations against Trump’s opponents, the president’s allies have “the effect of making his alleged criminality seem less unusual or less important,” Hemmer said.

Trump has been accused of many illegal activities and was impeached by the House for abuse of power and obstruction of Congress after he encouraged Ukraine’s president to investigate former vice president Joe Biden and his son, Hunter. The president was acquitted by the Senate. While Trump has denied wrongdoing, several of his aides and associates have pleaded guilty to numerous crimes.

In recent days, Trump has tried to shift attention from the twin economic and health-care crises, seizing on new revelations from the Justice Department that he claims are exculpatory for his administration. Trump and his allies have used the disclosures to try to make the case that a broad criminal conspiracy was launched against his presidency by a powerful cabal of government agents. Coverage of the decision by the Justice Department to drop charges against Trump’s former national security adviser, Mike Flynn, has taken priority over the historic pandemic in some conservative media in recent days.

Trump has tweeted that top officials in the Obama administration perpetuated the “the biggest political crime in American history, by far!” He has retweeted posts calling for a wide range of opponents to be “handcuffed and prosecuted,” “indited,” put “in prison” and left “sitting in a cell.”

Trump’s Mother’s Day storm of tweets came as the death toll from coronavirus continued to climb. The president has called for reopening the country’s economy, largely declaring victory against the virus and seeking to move on to other issues — including his reelection campaign.

But public health experts continue to warn that the complete focus of the federal government should be on stemming the spread of the virus, which has yet to be brought under control.

Testifying before the Senate health committee Tuesday, White House coronavirus task force medical expert Anthony S. Fauci predicted Americans would experience “suffering and death that could be avoided” and additional economic calamity if states ignore federal guidelines and reopen businesses too quickly. Several Republican senators on the committee said that the United States needed to step up its testing capability to deal with the pandemic.

More than 81,000 Americans have died from the virus, and more than 1.3 million have been infected. More than 30 million people have filed for unemployment benefits in recent weeks. Polling suggests most Americans disapprove of Trump’s handling of the pandemic.

The mass devastation has not stopped Trump from launching criminal accusations against people who have been criticized him. In recent days, he has targeted political opponents by amplifying allegations of sexual harassment, misuse of public airwaves and voter fraud against them.

Biden, the presumptive Democratic presidential candidate, said Trump’s willingness to lob allegations of criminal wrongdoing by his political opponents is an attempt to distract.

“This is all about diversion. This is a game this guy plays all the time,” Biden said in an interview with ABC’s “Good Morning America” on Tuesday. “The country is in crisis. We’re in an economic crisis, a health crisis. We’re in real trouble. He should stop trying to always divert attention from the real concerns of the American people.”