(Adds Nadler quote in paragraph 8; edits)
By David Morgan and Richard Cowan
WASHINGTON, July 12 (Reuters) - Two U.S. House committees are expected to delay former Special Counsel Robert Mueller's planned July 17 testimony for one week to allow more time for lawmakers from one of the panels to question him, sources said on Friday.
Mueller, who oversaw the federal investigation into alleged Russian interference in the 2016 U.S. presidential election, is now expected to testify July 24 before the House Judiciary and Intelligence committees, sources familiar with the plan said on the condition of anonymity because talks are continuing.
Lawmakers made conflicting statements about the hearing on Friday afternoon. Several predicted a delay, but some said a final agreement was not yet in hand.
In response to a query from Reuters, an aide to the House Judiciary Committee said in an email: "At this moment we still plan to have our hearing on the 17th and we will let you know if that changes."
The uncertainty posed an unwelcome distraction for Democrats, who have billed Mueller's testimony as a potential watershed moment that could focus attention on segments of his 448-page report that raise troubling questions about Republican President Donald Trump's efforts to impede the federal investigation.
The committees have not officially announced any format. But Mueller had been expected to appear on Wednesday in separate two-hour public hearings before the Judiciary and Intelligence committees.
The Judiciary Committee also sought to interview former Mueller aides Aaron Zebley and James Quarles behind closed doors on Wednesday. But Representative Steve Cohen, a Democrat, told reporters the two men would not appear, after the Justice Department directed them not to testify.
House Judiciary Chairman Jerrold Nadler declined to comment on Friday as he left Capitol Hill.
Lawmakers began to consider a delay when Judiciary Committee members balked at the unofficial arrangement for Mueller, because many of the panel's less senior lawmakers would not get time to ask questions.
"Everyone on the committee wants an opportunity to examine Mr. Mueller," said Representative David Cicilline, a senior House Judiciary Democrat. "We have been arguing for as much time as we can get. Obviously, we want to make sure that there's a full hearing."
Under a new plan, sources said the House Judiciary panel would get an additional hour for questions. But some of the committee's 24 Democrats and 17 Republicans could still be left out.
"That's a decision that will be collectively made, led by Chairman Jerry Nadler," said Representative Hakeem Jeffries, a Democrat who suggested there could be a way for some lawmakers to participate without asking questions of Mueller.
"Every single member of the House Judiciary Committee, on the Democratic and the Republican side, should be able to participate in the hearing in some way, shape or form."
Republican protests about the arrangements boiled over earlier this week, when Republicans accused House Intelligence Committee Chairman Adam Schiff of upstaging the Judiciary Committee, despite its primary jurisdiction over special counsel investigations.
House Intelligence has 22 members, about equal to the number of Judiciary members who were initially expected to question Mueller. Judiciary has 41 members.
In April, Mueller submitted the findings of his nearly two-year investigation to the Justice Department.
Mueller's investigation did not find evidence of collusion between Russia and the Trump 2016 presidential campaign. It made no final recommendation on whether there was obstruction of justice by Trump. (Reporting by David Morgan and Richard Cowan; editing by Jonathan Oatis and Bill Trott)
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