"Who's going to give back the young and beautiful lives (and others) that have been devastated and destroyed by the phony Russia Collusion Witch Hunt?" Trump tweeted Sunday morning.
It was unclear whom Trump was talking about, given that most of the people directly affected by the investigation have been limited to his inner circle and a handful of former campaign aides.
Trump instead referred to those hurt in romantic, generational terms.
"They journeyed down to Washington, D.C., with stars in their eyes and wanting to help our nation ... They went back home in tatters!" Trump continued.
Although a number of young aides have left Trump's White House – notably his former communications director Hope Hicks – most have departed as a result of the fierce infighting among administration factions, not because of the investigation into Russian meddling in the 2016 election and any possible Trump campaign involvement and whether the president obstructed justice.
Trump's focus on the investigation – even on a weekend typically reserved for mourning soldiers who died in combat – underscored the degree to which the issue continues to obsess and frustrate the president, who believes it is an effort to delegitimize his presidency. His chief of staff, John F. Kelly, told National Public Radio this month that Trump is "somewhat embarrassed" by the string of investigations.
One continuing issue has been whether Trump will sit for questioning by special counsel Robert Mueller. The president's lawyer and close adviser Rudy Giuliani, appearing on CNN on Sunday, declined to say directly.
Giuliani said Mueller's office, which has been negotiating the parameters of a potential sit-down, would probably limit questions to those involving whether the campaign colluded with Russian agents and whether Trump tried to obstruct the investigation into those efforts.
"The collusion part, we are pretty comfortable with because there has been none," Giuliani said. "The obstruction part, I'm not as comfortable with _ I'm not. The president's fine with it. He's innocent."
"I'm not comfortable because it's a matter of interpretation" including how one views Trump's rationale for firing FBI Director James B. Comey in the midst of the probe last year, Giuliani said.
Asked whether he thought the investigation is legitimate, Giuliani said "not anymore. I did when I came in."
Trump continued his campaign over the weekend of trying to sow distrust in the probe by calling Mueller's team of attorneys "13 Angry Democrats (& those who worked for President O)."
In fact, Mueller is a Republican and not all of the political affiliations of his team are known. Mueller was named FBI director by President George H.W. Bush in 2001 and stayed on during the Obama administration until 2013.
Trump also repeated his allegation that the FBI's use of informants _ a common practice in investigations _ amounted to spying on his campaign.
"With Spies, or 'Informants' as the Democrats like to call them because it sounds less sinister (but it's not), all over my campaign, even from a very early date, why didn't the crooked highest levels of the FBI or 'Justice' contact me to tell me of the phony Russia problem?" Trump asked in one tweet.
Republican Sen. Marco Rubio of Florida pushed back against that claim while appearing on ABC's "This Week," calling it appropriate to investigate a foreign adversary's potential interference with the democratic process.
The FBI appeared to be investigating "certain individuals who have a history that we should be suspicious of" rather than the campaign itself, he said.
"When individuals like that are in the orbit of a major political campaign in America, the FBI, who is in charge of counterintelligence investigations, should look at people like that," Rubio said. "But they're not investigating the campaign. They're investigating those people."
Trump's attacks on the media over the weekend may have been his most baffling.
In one of two Saturday tweets directed at The New York Times, Trump falsely claimed that one of its sources "doesn't exist." The paper quoted an administration official saying that reinstating a planned summit between Trump and North Korean leader Kim Jong Un on the scheduled date, June 12, would be logistically impossible.
"WRONG AGAIN!" Trump tweeted. "Use real people, not phony sources."
In fact, the source was not fake. He was a senior official who briefed reporters Thursday in a session set up by the White House press office, which set ground rules requiring that reporters not use his name. Whether Trump was aware of that is not known _ he often seems unaware of the work his staff does.
Trump, in calling the official "phony," was not only stating a falsehood and accusing The New York Times of making up a source, he was also compromising his officials' ability to speak on his behalf.
— Noah Bierman, Tribune Washington Bureau