(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.
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"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.
Democrats disagree, as the committee's top Democrat, Rep. Adam Schiff of California, says there are still dozens of witnesses the panel should call, as well as numerous subpoenas it should issue or enforce.
Democrats have pointed to two new events this week as reason to keep calling witnesses: Sam Nunberg's media blitz and reports that businessman George Nader attended secret meetings during the Trump transition -- and is cooperating with special counsel Robert Mueller.
Schiff specifically called for Nunberg to come before the committee after the onetime Trump campaign adviser suggested that then-candidate Donald Trump had advance knowledge of the June 2016 Trump Tower meeting.
"He is among, frankly, a fairly large group of witnesses that we still need to bring before our committee," Schiff said.
But Conaway saw little need to talk to Nunberg, who was fired from the campaign in 2015.
"I think we've explored that to death," Conway said of the Trump Tower meeting.
Still, the latest episodes stemming from Mueller's probe underscore how new developments could still emerge in that investigation that have the potential to alter the committee's conclusions, a possibility Republicans have acknowledged.
"I think we've found everything that can be found, and perhaps Bob Mueller can find more, I don't know," King said.
If Lewandowski -- who is returning to speak to the committee for a second time Thursday -- is actually the committee's final Russia witness, it will mark the end of a tumultuous chapter for a committee that's seen its Russia investigation hampered by partisanship, infighting and mutual distrust. In recent weeks the committee has been consumed by the fight over the memo on alleged Foreign Intelligence Surveillance Act abuses from House Intelligence Chairman Devin Nunes and the counter-memo from Schiff.
When the committee officially declares an end to the investigative portion of its probe, lawmakers on the panel expect they will write a final report -- and almost assuredly separate conclusions from Republican and Democratic.
But unlike the memo fight, the committee's Republicans plan to communicate with Democrats so that the two sides are at least on the same timeline for writing the report, according to sources familiar with the committee's discussions, even if they likely will come to drastically different conclusions.
Lewandowski will be the second senior Trump official to return to the committee this year after fights about the scope of testimony.
Steve Bannon was slapped with a subpoena in January during his first appearance before returning for additional questions last month, but he still would not answer questions about his time in the White House. Democrats said he should be held in contempt of Congress, but Conaway has deferred the matter for now.
Lewandowski limited the scope of his testimony in January to the time he spent on the Trump campaign. The former Trump campaign manager now is returning voluntarily, and Conaway told CNN on Wednesday he expects Lewandowski to answer questions about events through the end of the 2016 election campaign.
"We'll ask our questions and we'll see what he answers," Conaway said. "I don't know what he's got between his ears."
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