Behind the scenes at the Capitol, a struggle played out between lawmakers on the House Russia investigation in the leadup to the issuing of the first subpoenas, CNN reported last week. Democrats have pushed Nunes to relinquish his power over subpoenas -- the strongest tool they have to use in their investigative toolbox -- and instead hand the power to the new leader of the House Russian probe, Rep. Michael Conaway, R-Texas.

Republicans on the panel, meanwhile, have said that the subpoena power still resides with Nunes.

Asked over the weekend to respond to CNN's report that Nunes was still overseeing the committee's subpoenas, Schiff, one of the people who first called for the California Republican to recuse himself, said it was true, but he wished it were not the case.

"He does. I don't think that he should, given that he has stepped aside or recused himself," Schiff said Sunday on ABC's "This Week." "What I have been urging is that we have a committee vote. That's a procedure that's provided for in our rules. Or that the committee delegate to Mr. Conaway, with advice and consultation with myself. That's similar to what the Senate has done, and that's what I recommend we do here."

A Nunes spokesman did not return multiple requests for comment sent Wednesday evening and Thursday morning.

The Senate investigation continues providing a sharp contrast to the House's efforts. Last week, the Senate intelligence committee voted to give broad subpoena power to the two leaders of their investigation, Sen. Richard Burr, R-North Carolina, and Sen. Mark Warner, D-Virginia.

Sen. Ben Cardin, a Maryland Democrat, told CNN's Erin Burnett that Nunes' decision to issue subpoenas on his own "raises major questions. He had the power to issue a subpoena. It should never have been done without working with the Democrats."

Impact on investigation

Leaders of the House investigation have guided their probe back to normalcy over the past two months, since Nunes announced he would step aside. And Nunes was visibly absent from the House's second public hearing on Russia, which featured former CIA Director John Brennan.

But pressure has been mounting behind the scenes amid mounting questions about the extent of Nunes' recusal.

Nunes's visit to CIA headquarters to review intelligence related to Russia, rankled Democrats who said he was violating the spirit of his recusal. Conaway later said that the Russian intelligence Nunes saw was not related to the House investigation.

JUST WATCHED Flynn, Cohen issued subpoenas in Russia probe Replay More Videos ... MUST WATCH Flynn, Cohen issued subpoenas in Russia probe 02:32

"He's not involved in the Russia investigation. He's not interfering with me at all," Conaway said at the time.

Nunes continues to hold a powerful seat on the "Gang of Eight," a group that is given access to top-level classified information and is reserved for the the four leaders of the House and Senate -- House Speaker Paul Ryan, House Minority Leader Nancy Pelosi, Senate Majority Leader Mitch McConnell and Senate Democratic Leader Chuck Schumer -- and the top four members on the House and Senate intelligence committees.

Why he stepped aside

When Nunes announced he would step aside from the probe almost two months ago, the fighting had reached a fever pitch that looked certain to derail the House investigation.

At the beginning of April, Democrats were accusing Nunes of coordinating with the Trump White House to derail the House Russia probe. Nunes took a clandestine trip to the White House -- one day after then-FBI Director James Comey announced that the FBI had been investigating the Trump campaign since last July -- and returned, telling reporters he had discovered evidence which supported Trump's claims that he was a victim of surveillance by the Obama administration.

But as Nunes' story unraveled -- and news emerged that the intelligence he reviewed was provided by White House staffers -- pressure grew for him to step aside. On April 6, Nunes announced via a carefully worded statement that he would let three other Republicans "temporarily take charge" of the investigation because he had become the subject of an ethics investigation into whether he mishandled classified information.

"Chairman Nunes has offered to step aside as the lead Republican on this particular probe, and I fully support his decision," Ryan said at the time.

One day after he stepped aside, Nunes touted his strategy as a means to protect other Republicans from facing questions about his clandestine White House trip.

"I did something they never thought I would do -- I stepped aside and I gave them a gift. The gift is called Trey Gowdy," Nunes said in audio of a speech to fellow California Republicans obtained by the Los Angeles Times this week. "And guess what? When these ethics charges are gone, then I'm going to be back again. I would like to thank you all for all your support. I know a lot of you are disappointed, but there is a method to why I did this."

What's in a word?

A senior Republican aide said Wednesday that Nunes never actually promised to recuse himself from the probe.

"He didn't 'recuse' himself. That has a very specific legal definition and isn't accurate here," the aide said.

The aide argued that "temporarily stepping aside" and "recusing" are two entirely different things, and noted that Nunes still has an important job to fill as chairman of the House intelligence committee, including investigating any "unmasking" -- the revealing of US nationals swept up in routine surveillance of foreign officials -- in intelligence reports.

Rep. Adam Kinzinger, an Illinois Republican, called Nunes "honorable" Thursday on CNN's "New Day" -- but added that he had questions about Nunes' role in the Russia subpoenas.

"I hope he reveals and comes out and discusses it," Kinzinger said. "I thought he stepped away from the probe."