Former deputy attorney general Rod J. Rosenstein conceded Wednesday that, in hindsight, he would not have signed an application to continue monitoring a former Trump campaign adviser during the FBI’s investigation into Russian interference in the 2016 election, and claimed he did not know of the significant problems that have since been identified with it.

The comment came at a Senate Judiciary Committee hearing to examine the Russia probe, including flaws in applications to monitor former Trump campaign adviser Carter Page. The Justice Department inspector general found numerous errors and omissions in the applications, and the department has told a court it now believes it had “insufficient predication” to continue the surveillance.

Sen. Lindsey O. Graham (R-S.C.), a staunch ally of President Trump, asked Rosenstein, who signed one of the problematic applications, if — given what he knows now — he would have approved it. “No, I would not,” Rosenstein responded.

At a Senate Judiciary Committee hearing on June 3, former attorney general Rod J. Rosenstein contradicted a number of GOP theories about the Mueller probe. (The Washington Post)

Conservatives are likely to seize on the admission, and others from Rosenstein, as more ammunition for their attacks on the Russia investigation. Rosenstein offered some defense of steps he took in the took in the case — particularly his appointment of Robert S. Mueller III as special counsel to lead it — but at times he was conciliatory toward Republicans skeptical of the investigation.

After Graham asked if Rosenstein would agree there was ultimately “no there there” to support the “concept that the campaign was colluding with the Russians in August 2017,” Rosenstein responded, “I agree with that general statement.” In that month, Rosenstein wrote a memo detailing the scope of Mueller’s investigation; the probe was far from over.

But Rosenstein seemed to stress at other points that his conclusion about the lack of a conspiracy between the Trump campaign and Russia came only in hindsight. He noted, for example, that he “understood there was predication to investigate” when he wrote his scope memo, and added, “We investigate people who are not necessarily guilty, and so I didn’t have any presumption that these folks were guilty of anything.”

Rosenstein said of the Russia case, “I do not believe the investigation was a hoax” — which seemed to directly rebut a talking point of Trump’s. But soon after, Rosenstein said he could not “vouch for the allegations.”

“As we now know, the eventual conclusions were that Russians committed crimes seeking to influence the election and Americans did not conspire with them,” he said. Mueller’s report detailing his findings concluded there was not evidence to allege a conspiracy but that the Trump campaign “expected it would benefit electorally from information stolen and released through Russian efforts.”

Rosenstein said “appointing a special counsel was the best way to complete the investigation appropriately and to promote public confidence in its conclusions.”

“I still believe it was the right decision, under the circumstances,” he said. He added later, “I do not believe that Mr. Mueller was trying to get rid of the president.”

Rosenstein defended then-Attorney General Jeff Sessions’s recusal from the case, which put Rosenstein in charge, calling Sessions “one of the most principled people I’ve ever met in Washington.” The recusal enraged Trump, who to this day attacks Sessions over the matter. He also repeated a comment he made to The Washington Post after he went into private practice.

“I believe we got the big issues right,” he said.

Rosenstein is the first of potentially dozens of witnesses in an effort by Graham to investigate the investigation that upended Trump’s presidency and resulted in criminal convictions for several of his associates and campaign aides. In his opening statement, Graham played a clip of Rosenstein describing in a May 2018 appearance how the Foreign Intelligence Surveillance Act process typically works — with a career law enforcement official swearing to the truth of an application — and then took aim at the comments.

“What brings us here is the fact it didn’t work that way,” Graham said. “We’re trying to find out how that happened.”

Graham also suggested he would be conducting a broad look at the Mueller investigation — including the reason for Mueller’s appointment.

“We’re going to look hard,” he said.

Democrats have bristled at the probe, suggesting the Russia case already has been aggressively scrutinized by the Justice Department’s internal watchdog and that Republicans seem to be trying to undercut the legitimate work Mueller did because they want to please Trump and help his reelection campaign.

The Justice Department inspector general last year lambasted the FBI for its handling of the warrant to monitor Page, though he said information had been kept from Rosenstein and other high-level officials before the warrant application was approved. Rosenstein said he did not know of many of the problems, including that an FBI lawyer doctored a document used as part of the process.

Some Republican lawmakers took aim at Rosenstein, suggesting he did not do enough to ensure the accuracy of the application he signed. Rosenstein conceded he was not sure he had “read every page.” White House press secretary Kayleigh McEnany seized on that at a briefing Wednesday, saying, “It’s really astonishing to hear from him that he’s not sure he read every page of that warrant, but I suppose it’s encouraging to hear with his 20/20 hindsight that he wouldn’t have signed off on it.”

In a particularly heated exchange with Sen. Josh Hawley (R-Mo.), Rosenstein accepted responsibility but suggested the lawmaker should focus on future fixes.

“I am accountable for it, but the question is, why did it happen?” Rosenstein said, adding later, “Yelling at me is not going to solve the problem.”

Sen. Dianne Feinstein (Calif.), the highest-ranking Democrat on the committee, conceded that Justice Department Inspector General Michael Horowitz had found serious deficiencies in the warrants on Page, as well as broader problems in how the FBI uses the Foreign Intelligence Surveillance Act. But she noted that Horowitz also found the FBI had good cause to open an investigation into the Trump campaign.

Rosenstein was far more guarded in addressing another controversy that he was questioned about: the Justice Department’s recent move to try to drop the criminal case against former Trump national security adviser Michael T. Flynn.

Flynn pleaded guilty in 2017 to lying to the FBI about conversations he had with a Russian diplomat but later changed defense teams and sought to undo the case. Attorney General William P. Barr tapped U.S. Attorney Jeff Jensen in St. Louis to look into the matter, and Jensen ultimately uncovered FBI notes, which Flynn’s defense team has alleged show Flynn was entrapped.

At Jensen’s recommendation, Barr decided FBI agents did not have a good reason to interview Flynn in the first place, and thus his lies were not “material” to any case — a requirement to substantiate the charge to which he admitted.

Rosenstein, who was nominated by Trump to be deputy attorney general and confirmed in April 2017, was not leading the investigation when the FBI spoke to Flynn. But he was supervising the matter when Flynn later pleaded guilty and agreed to cooperate with Mueller’s investigation.

Sen. Charles E. Grassley (R-Iowa) confronted Rosenstein about the matter, saying that at a June 2018 meeting the two had, Rosenstein refused to turn over case-related documents.

“It’s clear you were misleading me, Congress and the American people when you suggested we should be satisfied with Flynn’s plea agreement,” Grassley said.

Rosenstein responded that he was only reluctant to turn over materials because of the Justice Department’s long-standing policy of not giving lawmakers access to such documents in a case that is pending in court.

Rosenstein said he approved the case against Flynn because “the evidence demonstrated his guilt, and he and his attorneys admitted his guilt.” He said much of what has been revealed recently was “news to me.”

“I obviously didn’t know there was exculpatory evidence,” he said. Many legal analysts have disputed that the new evidence exonerates Flynn.

Rosenstein also took aim at former acting FBI director Andrew McCabe, alleging McCabe was “not fully candid with me” in the early days of his leading the bureau and the Russia case in May 2017. McCabe, Rosenstein said, did not for at least a week turn over memos from James B. Comey — whom Trump had just fired as FBI director — documenting what Comey saw as troubling interactions with the president.

Rosenstein also disputed McCabe’s allegations that, during that time period, Rosenstein had suggested wearing a wire to surreptitiously monitor Trump, or invoking the 25th Amendment to remove him from office. Rosenstein has more vaguely denied the allegations in the past; McCabe documented the alleged incidents in contemporaneous memos. In a statement Wednesday, McCabe said Rosenstein’s testimony “looks to be yet another sad attempt by the President & his men to rewrite the history of their actions in 2017” and noted he had briefed Rosenstein on Comey’s memos days after Comey was fired.

“I did not suggest or hint at secretly recording President Trump,” Rosenstein said. “I have never in any way suggested that the president should be removed from office under the 25th Amendment,” which establishes a process for the Cabinet to force removal if a president is unable to perform his duties.

Rosenstein has long had a complicated relationship with Trump. Even though the president nominated him as deputy attorney general, he later derided the Justice Department leader as a “Democrat from Baltimore.” But Rosenstein has also taken some heat from the left for being willing to mollify the president.

After the New York Times reported the allegations that Rosenstein had contemplated wearing a wire to record Trump, or invoking the 25th Amendment to oust him, Rosenstein sought to assure the president in a phone call that he would treat him fairly, according to officials with knowledge of the call.

“I give the investigation credibility,” Rosenstein said, according to an administration official with knowledge of what was said during the call. “I can land the plane.”

On Wednesday, Rosenstein vaguely disputed he had said that.

“I do not believe I’ve ever used those words, ‘I can land the plane,’ ” he said. “But what I can tell you is what I always said when anyone asked me about the investigation, which was that we would complete it appropriately and expeditiously, and I made no inappropriate commitments.”