Attorney General Jeff Sessions told a Senate panel Wednesday that he would not discuss the content of his conversations with President Trump about the May firing of FBI Director James Comey, citing the president’s privileged communications with his executive staff.

Sessions said the privilege cannot be breached without Trump's consent. He called it a “core privilege of the president.”

"I would just urge us all to respect the legitimacy of any president’s right to seek advice in private. This is not a little matter," Sessions said.

Sessions' appearance Wednesday was his first before the Judiciary Committee, which oversees the Justice Department, since his confirmation hearings in January. The nine-month gap between appearances left senators with multiple questions, some of which Sessions answered and some he didn't.

Trump fired Comey in the midst of the FBI's investigation into possible collusion between the Trump campaign and Russian officials.

Sen. Sheldon Whitehouse, D-R.I., challenged Sessions’ refusal to divulge the nature of his discussions with the president regarding the Comey firing, claiming that the attorney general was invoking privilege even though the president has not directly indicated that the conversations were covered by the privilege.

Sessions defended his position, saying that the president had broad authority to retain the confidentiality of his discussions with Cabinet members.

Committee Democrats pressed the attorney general Wednesday on his role in the Comey firing. Sessions declined to answer whether Trump had discussed firing Comey to “lift the cloud” of the Russia investigation.

At the same time, however, he told California Sen. Dianne Feinstein, the committee’s senior Democrat, that he did not believe there was full understanding of the “significance of the error” in Comey’s handling of the investigation into Hillary Clinton’s use of a private email server while she was secretary of State.

Sessions said he had agreed with Deputy Attorney General Rod Rosenstein’s assessment that Comey had “usurped” the authority of the Justice Department by announcing the initial closure of the investigation and recommending that no criminal charges be brought.

Comey told the Senate Intelligence Committee earlier this year that he felt compelled to make the recommendation to close the investigation because he believed that then-Attorney General Loretta Lynch had compromised herself when she met with former president Bill Clinton on an airport tarmac in the midst of the email inquiry.

At one point, Sen. Patrick Leahy, D-Vt., suggested that Trump was using Sessions as part of "a façade" to provide cover to the president for firing Comey over his handling of the Russia inquiry.

“I’m not part of a façade,’’ Sessions said.

Sessions said he had not been interviewed by special counsel Robert Mueller’s team investigating Russian interference in the 2016 election.

“No,” Sessions said, responding to a question posed by Leahy. He hesitated before answering, saying that he may have to consult the special counsel. But when pressed, he said that no interview had taken place.

Sessions vowed to “absolutely” cooperate with Mueller’s investigation if asked to do so. After checking with his staff, Sessions said the special counsel has not contacted his office to request an interview.

Of the ongoing special counsel’s inquiry, Sessions said the "process has to work its will."

“I’ve known special counsel Mueller for many, many years. I think he will produce the work in a way he thinks is correct, and history will judge," Sessions said.

No collusion

Asked whether he colluded with the Russians as part of their interference in the 2016 election, Sessions offered an emphatic: "No."

He went on to say that he is not aware of any collusion between anyone in the Trump campaign and Russian officials.

"I don't believe it happened," Sessions said.

Three congressional committees, including the Senate Judiciary Committee, are investigating Russian interference in the 2016 election and possible collusion between the Trump campaign and the Kremlin.

Earlier, Leahy took Sessions to task for providing “false” testimony during his confirmation hearing when the attorney general indicated that he had no contact with Russia officials.

Sessions denied that he provided inaccurate information during the January hearing, and later said that his contacts with Russian ambassador Sergey Kislyak, which he did not disclose during confirmation, involved no discussion of Russian interference in the election.

“I don’t recall any conversation about the details of the campaign,” Sessions said.

The disclosure of Sessions’ contacts with the Russian ambassador in part prompted the attorney general to recuse himself on all matters related to the Russia inquiry.

The action led to the appointment of Mueller, a former FBI director, to manage the investigation as a Justice Department special counsel.

Sen. Al Franken, D-Minn., pressed Sessions on his failure to disclose his contacts with the Russian ambassador during the attorney general’s confirmation hearing, and criticized Sessions’ varying accounts of at least two of the meetings since that hearing.

"I conducted no improper discussions with Russians at any time," Sessions shot back. "That’s been the suggestion that you raised, Senator Franken."

Noticeably irritated when Franken interrupted, Sessions appealed to Grassley: "I don’t have to sit here, Mr. Chairman, and not have a chance to respond. I’m disappointed."

Asked by Sen. Ben Sasse, R-Neb., whether the U.S. government is doing enough to prevent Russian interference in future elections, Sessions responded: "We're not."

Opioid epidemic

On another topic, Sessions addressed the fatal scourge of opioid abuse as the Trump administration wrestles with how it intends to respond.

Sessions called for stricter legislation limiting the mass distribution of the highly addictive and potent drug.

“We are in the midst of the deadliest drug epidemic this country has ever seen,’’ Sessions said. “Our country has seen nothing like it."

He added that "there can be no doubt that we need much stricter accountability’’ in the distribution of opioids.

Sessions' appearance also represents his first return to Capitol Hill since he testified in June before the Senate Intelligence Committee investigating Russia’s interference in the 2016 election.

During that combative two-hour hearing, Sessions rejected any suggestion that he colluded with Russian officials while advising Trump’s campaign, calling such assertions “an appalling and detestable lie.”

More than a month after his June testimony before the Senate Intelligence panel, it was disclosed that Kislyak told his Russian superiors that he and Sessions had discussed Trump’s campaign and policy matters related to Russia.

The ambassador’s discussions with the Kremlin were first reported by The Washington Post, which referred to intercepted communications by U.S. intelligence.

Sessions had previously denied that his contacts with Kislyak had included discussions related to the campaign and Russia’s interests. He repeated those denials Wednesday.

Recent Justice actions

Apart from Russia, the attorney general was grilled on a constellation of recent Justice Department actions — from its management of immigration enforcement issues, the pursuit of harsher penalties against criminal suspects and the agency’s rollback of Obama administration civil rights policy.

A flashpoint in the Sessions’ hearing erupted when Sen. Richard Durbin, D-Ill., asserted that the Justice Department policy that now blocks some federal grants from cities that do not cooperate with immigration authorities was making matters worse in violence-plagued Chicago.

“Mr. Attorney General, you are not helping us solve the murder problem in Chicago,” Durbin called out.

Sessions responded: “Chicago is a great city. Many good things are going for it. I do think the murder rate is a cloud over the city. I’m worried about the health and morale of the Chicago Police Department.”

Republican lawmakers lauded the administration’s controversial action to wind down the program known as Deferred Action for Childhood Arrivals, enacted during the Obama administration.

Trump has expressed interest in striking an agreement to accommodate some of the 2 million young immigrants known as "Dreamers" who were brought to the U.S. as children. However, Sessions said Wednesday he had concerns about the possibility that Dreamers, if granted citizenship or permanent legal status, might seek to bring other family members to the country illegally to join them.