(CNN) Former Trump campaign manager Corey Lewandowski is scheduled to be interviewed by the House Intelligence Committee on Thursday, and he could be one of the last major witnesses to appear as part of the panel's Russia investigation.

Rep. Mike Conaway and other Intelligence Committee Republicans are signaling they're ready to end the investigative phase of their Russia probe and move on to writing the final report, while Democrats say there are still scores of witnesses the committee needs to speak with. Conaway, the Texas Republican leading the committee's Russia investigation, hasn't ruled out calling additional witnesses, but he's hinted that no big names remain on his list.

"Something may pop up. We're coming toward the end of it," Conaway said when asked about future witnesses. "Every investigation ought to have a conclusion, including this one."

Other committee Republicans have been more forceful in saying it's time to shut down the House Intelligence Russia probe. Rep. Tom Rooney of Florida pointed to the leaks of White House communications director Hope Hicks' testimony last week as reason to end the investigation, while Rep. Pete King of New York says the committee has learned all it can.

"To me, I don't see anything else that's out there that hasn't been explored," King told CNN.