(This January 16 story corrects sixth paragraph to say Republicans hold 53 rather than 52 seats in the 100-seat Senate.)

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WASHINGTON (Reuters) - Senate Democratic leader Charles Schumer said on Wednesday he will oppose President Donald Trump’s attorney general nominee, William Barr, saying he is not convinced that Barr will protect Special Counsel Robert Mueller’s Russia probe or provide Congress with a full report on Mueller’s findings.

“We do not have the kind of strong and clear commitments to the report being issued and there being no interference in the investigation that are needed, particularly now, with President Trump treating the Justice Department as he has,” Schumer told reporters following a private meeting with Barr.

Schumer’s comments come one day after Barr appeared for his confirmation hearing before the Senate Judiciary Committee, where Barr vowed he would let Mueller complete his investigation into whether Trump’s campaign colluded with Russia and provide the public with as many details as possible on Mueller’s conclusions.

Trump has denied colluding and has called the investigation a witch hunt.

Schumer’s opposition to Barr’s nomination is not likely to prevent the Senate from confirming him as attorney general.

Barr enjoys broad support from Republicans, who hold 53 Senate seats. Only a simple majority in the 100-seat chamber is needed to approve a nomination.

However, Schumer’s concerns could signify that Barr will be confirmed with little or no Democratic support - a similar outcome to former Attorney General Jeff Sessions, who won confirmation with the support of only one Democrat.

Democrats raised concerns about Barr’s nomination after learning that Barr had sent a 19-page legal memo to top Justice Department officials and Trump’s lawyers calling Mueller’s probe into whether Trump obstructed justice “fatally misconceived.”

Barr said on Tuesday that the memo was narrowly focused on one aspect of the law and did not question the rest of Mueller’s investigation.

Schumer came out against Barr’s nomination after learning of the memo, but said he met with Barr on Wednesday in hopes he could be convinced to change his vote after Barr’s “nice words at the hearing.”

The Justice Department’s special counsel regulations require Mueller to provide a confidential report to the attorney general with his findings, and give the attorney general discretion to release details publicly.

Barr has pledged to make as much information public as he can by law.

But Schumer said that is not enough.

“I asked him, Would he issue the full Mueller report with only redactions if intelligence agencies said it would compromise sources? ... He would not give that assurance,” Schumer said.

Schumer also said Barr declined to promise that he would not block Mueller from interviewing certain witnesses or pursuing other areas of investigation.