(CNN) Sources on the Senate Intelligence Committee suspect that House Intelligence Chairman Devin Nunes and his staff were behind the leak of Sen. Mark Warner's text messages with a lobbyist for a Russian oligarch.

Burr said Thursday that he and Warner had met with House Speaker Paul Ryan simply to give him an "update" of their investigation. But a source familiar with the matter said that the two raised concerns about some of Nunes' tactics while meeting with him about their inquiry. Burr and Warner for months have been privately and publicly distancing themselves from Nunes, who has become a polarizing force within the House Intelligence Committee.

The speaker responded that he would not intervene in their dispute with the House Intelligence Committee.

"The speaker heard the senators on their concerns and encouraged them to take them up directly with their counterparts," said Ryan spokeswoman AshLee Strong, who declined to comment further.

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