Trump campaign submits over 20,000 pages of documents in Russia probe The documents were handed over in compliance with a Senate panel investigation.

 -- Donald Trump's presidential campaign, son Donald Trump Jr. and former campaign manager Paul Manafort turned over thousands of documents to the Senate Judiciary Committee in compliance with the panel's requests as it investigates possible Russian interference in the 2016 presidential election, a committee spokesperson told ABC News on Tuesday.

The Trump campaign sent more than 20,000 pages of documents to the committee last Wednesday, the deadline to submit documents, and Manafort handed over about 400 pages, including his foreign-advocacy paperwork, on the same day, according to the spokesperson.

Trump Jr. submitted about 250 pages on Friday, the spokesperson said.

In letters to Trump Jr. and Manafort, the Judiciary Committee asked for all documents related to their June 2016 meeting with Russian lawyers, as well as any communications with or records of attempts to obtain information from Russians about Hillary Clinton or the 2016 presidential campaign, according to the spokesperson.

Fusion GPS — the opposition research firm linked to a controversial dossier containing numerous allegations about Trump and his campaign — and its owner, Glenn Simpson, have yet to turn over documents, the spokesman said.

The panel said it hopes to have staff-transcribed interviews with all three men in a closed session before they testify in a public hearing but that negotiations with them are ongoing.