WASHINGTON (AP) — Senate Majority Leader Mitch McConnell is declaring "case closed" on the Russia probe and potential obstruction by President Donald Trump.

The Republican leader, in his most significant public comments yet on the investigation, is expected to outline in a Tuesday speech how special counsel Robert Mueller's "exhaustive" probe went on for two years and is now complete. The remarks are being billed as his final thoughts on the topic.

"It's finally over," McConnell is expected to say.

Republicans, taking their cues from Trump, are eager to push past the investigation as Democrats are pressing for further oversight of the White House and the president's handling of the Mueller probe.

McConnell is expected to question if others are ready to move on from the "breathless conspiracy theorizing?" The Kentucky senator will suggest he doubts so.

On Tuesday, House Democrats are set to meet with Attorney General William Barr as they negotiate to see a full, unredacted Mueller report.

The House Judiciary Committee is poised to vote to hold Barr in contempt of Congress for the Justice Department's failure to comply with a subpoena to turn over the report and its underlying documents. That vote could happen as soon as Wednesday.

It's the opening salvo in what could be a lengthy, acrimonious court battle between House Democrats and the Trump administration over Mueller's findings.

Judiciary Committee Chairman Jerrold Nadler said late Monday that the hopes to make "concrete progress" toward resolving the dispute over gaining access to the report.

Nadler, D-N.Y., has cited the Justice Department's failure to provide the full text of Mueller's report by the Monday morning deadline. He said Barr's failure to comply with a subpoena left Democrats with "no choice but to initiate contempt proceedings."

The movement to hold Barr in contempt reflects the deepening rift between Democrats and Barr, whom they accuse of spinning the results of Mueller's investigation to Trump's benefit. Barr, in a memo summarizing Mueller's investigation , said there was insufficient evidence that Trump obstructed justice, a conclusion Democrats fiercely dispute.

Nadler said the version of Mueller's report that has already been released to the public offered "disturbing evidence and analysis that President Trump engaged in obstruction of justice at the highest levels." Now, he said, lawmakers need the full version and the underlying evidence "to determine how to best move forward with oversight, legislation and other constitutional responsibilities."

The committee said contempt proceedings could be postponed if the attorney general makes a "good faith" effort to comply with the committee.

In a possible thaw, Nadler said Monday evening that the Justice Department had agreed to meet with his staff Tuesday.

Justice Department spokeswoman Kerri Kupec said earlier that the department has "taken extraordinary steps to accommodate the House Judiciary Committee's requests for information" regarding Mueller's report but that Nadler had not reciprocated. She noted that Democrats have refused to read a version of Mueller's report with fewer redactions that has already been provided to Congress.

Kupec said that officials were continuing to engage with the committee and that Nadler's staff had been invited to the department "to discuss a mutually acceptable accommodation."

If the committee approves the contempt resolution against Barr, as expected, it would head to the full House for final approval. But that step is unlikely to lead to criminal charges. A House vote would send a criminal referral to the U.S. attorney for the District of Columbia, a Justice Department official who is likely to defend the attorney general.

Yet by pursuing contempt, Democrats hope to send a message to the Trump administration about their willingness to invoke congressional powers in the majority. Beyond Mueller's report, House Democrats have, so far mostly unsuccessfully, subpoenaed administration witnesses and made efforts to gain access to Trump's personal and business financial records. Trump has said he will block those efforts, declaring he will "fight all the subpoenas."

Democratic House leaders could file a civil lawsuit against the Justice Department to obtain the Mueller report, an option that could take months or even years to resolve. Some committee members have suggested they also could fine Barr as he withholds the information. They could also open impeachment proceedings against Trump, though House Speaker Nancy Pelosi has said she's not interested in doing that, for now.

Republicans have lambasted the Democratic tactics as overreach and defended Barr. The top Republican on the Judiciary Committee, Rep. Doug Collins of Georgia, said "Democrats have launched a proxy war smearing the attorney general" when their anger actually lies with the president.

There is precedent for sitting attorneys general to be held in contempt of Congress. In 2012, the House held then-Attorney General Eric Holder in contempt over a botched gun-tracking operation known as Fast and Furious. Republicans cited the Justice Department's failure to turn over, without any preconditions, documents related to the risky operation. The Justice Department took no action to prosecute the attorney general.

Mueller's report — now a best-seller even in redacted form — states that his investigation could not establish a criminal conspiracy between the Trump team and Russia. However, it did not reach a conclusion on whether Trump obstructed justice. Mueller didn't charge Trump but wrote that he couldn't exonerate him, either.

House Judiciary Democrats say Congress is "the only body able to hold the president to account" since the Justice Department has a policy against indicting a sitting president.

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Associated Press writer Eric Tucker contributed to this report.