Former FBI Director James Comey on Sunday took responsibility for what the Justice Department's watchdog described as concerning and fundamental errors the FBI made in the course of its investigation into Russian attempts to influence President Donald Trump's campaign.

But Comey also claimed the Justice Department inspector general's report had vindicated both himself and the agency he used to lead by saying no political bias had driven the launch of what turned into a years-long investigation of Russian efforts to connect with Trump's campaign and influence the 2016 election.

Later Sunday, the president himself cast doubt on the Justice Department's watchdog, Michael Horowitz, saying he was appointed by President Barack Obama. He also suggested Comey could face jail time.

In an interview with "Fox News Sunday," Comey said, "As director, you are responsible for this," referring to errors made in the course of the probe.

"I was responsible for this," Comey said. "And if I were still there I would be doing what Chris Wray is doing about this...figuring out, so how did this happen, and is it systemic?"

Horowitz's report found that the FBI mishandled parts of its application to monitor Trump campaign aide Carter Page. Though the report said the overall investigation was justified and not launched for political reasons, Horowitz detailed 17 significant errors or omissions in the surveillance applications on Page.

"We are deeply concerned that so many basic and fundamental errors were made by three separate, hand-picked investigative teams on one of the most sensitive FBI investigations, after the matter had been briefed to the highest levels within the FBI," Horowitz said in testimony before the Senate Judiciary Committee this week.

After Horowitz publicly concluded the investigation was properly launched, Attorney General William Barr and U.S. Attorney for Connecticut John Durham, a prosecutor Barr tapped to lead another review of the Russia probe, immediately criticized that finding.

In Comey's interview with Fox, host Chris Wallace pointed to past remarks Comey made in which he said the FBI followed the process to obtain the surveillance warrants properly.

"He's right, I was wrong," Comey said. "I was overconfident in the procedures that the FBI and Justice had built over 20 years. I thought they were robust enough."

Comey, though, pointed to the report's other findings, adding that Horowitz "doesn't conclude there was intentional misconduct." When asked about his recent assertion that Horowitz "vindicated" him —despite the watchdog's statement to Congress that no one was vindicated based on the report — Comey responded that "maybe it turns upon how we understand the word."

'What I mean is that the FBI was accused of treason, of illegal spying, of tapping Mr. Trump's wires illegally, of opening an investigation without justification, of being a criminal conspiracy to defeat and unseat a president," Comey said. "All of that was nonsense. I think it's really important that the inspector general looked at that and the American people, your viewers and all viewers understand that's true."

"But, he also found things we were never accused of, which is real sloppiness, and that's concerning — [and] as I said all along, has to be focused on," Comey said. "If I were director, I'd be very concerned about it and diving into it."

Trump tweeted on the Horowitz report and Comey Sunday afternoon.

"As bad as the I.G. Report is for the FBI and others, and it is really bad, remember that I.G. Horowitz was appointed by Obama," Trump said. "There was tremendous bias and guilt exposed, so obvious, but Horowitz couldn’t get himself to say it. Big credibility loss. Obama knew everything!"

"So now Comey’s admitting he was wrong," Trump added in a second tweet. "Wow, but he’s only doing so because he got caught red handed. He was actually caught a long time ago. So what are the consequences for his unlawful conduct. Could it be years in jail? Where are the apologies to me and others, Jim?"

House Intelligence Chairman Adam Schiff, D-Calif., on Sunday pointed to the report's top-line takeaway that the investigation had been properly predicated.

"They were right to seek a FISA on Carter Page and there wasn't some deep state conspiracy," Schiff said on "Fox News Sunday." "There was no spying on the Trump campaign. There was no effort based on political bias to open the investigation, it was properly predicated. But there were nonetheless serious abuses of FISA which were not apparent two years ago but which have become apparent now with 170 witnesses interviewed and two million documents reviewed by the I.G."

Schiff added he was "certainly willing to admit the inspector general found serious abuses of FISA that I was unaware of."

"Had I been aware of them, yes, I would've called out the FBI at the same time," he continued. "But I think it's only fair to judge what we knew at the time, not what would be revealed two years later. But yes, there were very serious abuses of the FISA process, they need to be corrected, we need to make sure they never happen again."