WASHINGTON -- Republicans have seized on new developments in the Hillary Clinton email controversy as the issue that could help Donald Trump make up ground in the final presidential debate -- if he can hammer home the message.

Republican congressional leaders are alleging a coverup following news that the State Department had asked FBI officials to lower the classification of a sensitive email. FBI notes released Monday revealed discussion of a "quid pro quo" in trying to get the email reclassified, though both State and FBI officials deny any bargaining took place.

Trump called it "one of the great miscarriages of justice" in history. But with Wednesday's debate approaching, Trump and his campaign have had trouble sticking to the message.

The candidate has continued his controversial warnings that the election is "rigged," angering his fellow Republicans who worry his rhetoric will hurt public faith in elections. And as news about the emails hit, Melania Trump made her first public comments about the allegations of sexual assault and misconduct lodged at her husband.

In an interview with Fox News aired Tuesday, Mrs. Trump said she believes the accusations were co-ordinated by political rivals: "They want to damage the presidency of my husband, and it was all planned, it was all organized from the opposition."

Trump's comments carried echoes of Clinton's allegations of a "vast right-wing conspiracy" organized to raise similar allegations against her husband two decades ago. The last presidential debate was dominated by discussion of Trump's treatment of women and Trump's attempts to revive Bill Clinton's history.

It was unclear whether Wednesday's final faceoff in Las Vegas would return to those issues. Clinton planned to spend Tuesday in New York preparing for the debate in Las Vegas. Trump was slated to hold rallies in Colorado.

The disclosure of FBI documents revives questions about Clinton's use of personal email during her time as secretary of state. The issue that has dogged her campaign and damaged voters' trust in her even as she remains the favourite ahead of the Nov. 8 vote.

The document released Monday show a State Department Undersecretary for Management Patrick F. Kennedy, a former close Clinton aide, contacted an FBI official seeking to change an email's classification, a move that would have sent it to the archive, out of public view. Notes on the conversation describe discussion about a "quid pro quo" in which the email's classification would be changed and State would allow the FBI to place more agents in countries where they hadn't been permitted.

The records indicate that Kennedy made that suggestion, but both the FBI and State Department said Monday that it was the unidentified FBI official. Neither the declassification nor the increase in agents occurred.

Clinton campaign allies argued Tuesday that the documents show bureaucratic haggling.

"None of this has anything to do with Hillary Clinton. She wasn't involved in this at all," said Rep. Jerry Nadler, a Democrat from New York and a Clinton ally. Nadler said "maybe" the conduct of the officials involved "should be looked at."

The news came as Clinton is trying to expand her edge over Trump -- even in Republican territory. Her campaign announced Monday it was launching a new push in Arizona, including a campaign stop in Phoenix by first lady Michelle Obama, one of Clinton's most effective surrogates.

An additional $1 million is going into efforts in Missouri and Indiana, both states with competitive Senate races, and a small amount of TV time is being bought in Texas and media appearances are scheduled in Utah.

On the other side, Trump's campaign dramatically expanded its ad buys in seven battleground states and announced plans to launch a $2 million advertising blitz in long-shot Virginia.

Associated Press writers Thomas Beaumont in Des Moines, Michael Biesecker and Eric Tucker in Washington and Jill Colvin in Green Bay contributed to this report. Hennessey reported from Washington