"All they have is a whistleblower who has disappeared. Where is he? He is gone. Then they have the second whistleblower, the second whistleblower, where is he? He disappeared. Then they have an informant, oh, the informant, where is he?" Trump said in an exchange with ABC News White House Correspondent Cecilia Vega.
The president repeatedly floated the theory that the whistleblower received "second and third-hand information" from Schiff, chairman of the House Intelligence Committee -- one of several committees investigating Trump.
"I think that there probably was not an informant. The informant went to the whistleblower, the whistleblower had second and third-hand information. You remember that. It was a big problem. But the information was wrong. So, was there actually an informant? Maybe the informant was Schiff. It could be shifty Schiff. In my opinion it is probably Schiff," Trump said.
Asked by Vega whether it was a foregone conclusion that the House will impeach him, the president said the Democrats "want to impeach me, because it is the only way they’re gonna win."
"The president of the United States should be allowed to run the country, not have to focus on this kind of crap," he said.
Blasting the ongoing probe on the Hill, Trump said Congress is interviewing "ambassadors who I have never heard of," but then said, "I have great respect for some of them."
The president went on to say that many of those officials had been placed in their positions during the Obama administration and the "Never Trumper Bush era" and that "the good news is they are dying off fast."
"They’re on artificial respiration I think," Trump said.
The president praised the cohesion among the Democratic ranks as their one virtue, noting that they don’t have politicians like Utah Republican Sen. Mitt Romney, who has harshly criticized Trump both over the Ukraine affair and Trump's withdrawal of U.S. forces from northeastern Syria.
"I think the Democrats fight dirty," Trump said. "I think they are lousy politicians. The two things that they have, they are vicious and they stick together."
House Speaker Nancy Pelosi on Monday distributed a four-page "fact-sheet" outlining what Democrats view as the strongest case against Trump leading to impeachment.
As evidence of a "shakedown," Pelosi highlights the rough transcript the White House released from Trump’s July 25 call with the Ukraine president and claims it "paints a damning picture of Trump abusing his office by pressing a foreign government to interfere in our 2020 elections."
"President Trump has betrayed his oath of office, betrayed our national security and betrayed the integrity of our elections for his own personal political gain," the fact sheet argues.
The fact sheet also includes texts from State Department officials, including one in which Ambassador Bill Taylor says, "I think it’s crazy to withhold security assistance for help with a political campaign" as evidence of a "pressure campaign"
The whistleblower's complaint about the call that kicked off the impeachment inquiry is cited as as of evidence of a "cover-up."
Asked if he had any concerns about alienating Republicans with his decision to pull U.S. troops out of Syria, Trump said, "No, I don't think so, at all."
ABC News' Benjamin Siu and Elizabeth Thomas contributed to this report.