By Tom LoBianco

CNN

WASHINGTON (CNN) -- The House Intelligence Committee's first open hearing on Russia exposed a partisan rift between the committee's Republicans and Democrats that threatens to only grow bigger as they dig deeper into the possible ties between President Donald Trump's campaign and Russian operatives.

Through the lead-up to Monday's hearing, House Intelligence Chairman Devin Nunes and the panel's top Democrat, Rep. Adam Schiff, coordinated closely -- holding news conferences together, sending joint requests for information from the Justice Department and even agreeing on the first batch of witnesses to call.

But Monday's marathon questioning of FBI Director James Comey and National Security Agency Director Mike Rogers split almost evenly between Democrats pressing for more information on the Trump campaign's ties to Russia and Republicans seeking details on who leaked details of the FBI's investigation to the press.

And the rift could only widen in the coming weeks as both parties negotiate their next batch of witnesses, which could include former National Security Adviser Michael Flynn, former Trump campaign chairman Paul Manafort and other aides at the center of the FBI's investigation.

House Democrats on the Intelligence Committee cautioned their Republican colleagues Tuesday against getting in the way of calling people like Flynn and Manafort to testify.

"There are some enduring lessons of history -- which is eight or nine times out of 10, it is the cover-up that will get you. So don't be engaged in any effort here that seeks to sequester the truth, because that will ultimately be more damaging than whatever it is we may find out," said Rep. Denny Heck, a Washington Democrat on the committee. "The cover-up will always kill you, so resisting is not healthy in any way."

And Rep. Jackie Speier, a veteran Democrat on the panel, said that she is prepared to try and force Flynn and Manafort to come before the committee.

"If they need to be subpoenaed they will be subpoenaed -- I feel that strongly about it," Speier said. "And if this committee is worth its salt at all, it has to recognize you cannot complete an investigation without interviewing them and (former British intelligence officer) Christopher Steele, and (former Trump adviser) Roger Stone and (former Trump foreign policy adviser) Carter Page and the web of operatives that had relationships with Russia."

But Nunes said he's fine with some divisions on the committee and argued that they are already being bridged well.

"I don't think that's a problem," Nunes told CNN Monday. "At the end of the day there could be disagreements, which I expect there to be disagreements -- you're not going to get 435 members to agree on anything. I think there will be some things we can agree on, some things we won't be able to agree on, but at the end of the day I think we'll be able to put together a useful report."

Nunes, as the chairman, has a final say in how the investigation is run, but he has been coordinating closely with Schiff and, in some ways, the House investigation has emerged on two tracks -- with Democrats and Republicans focusing almost exclusively in their pet areas.

"At the end of all that you'll have people in separate corners," Nunes said. "And, honestly, look, a lot depends on the FBI. What are they actually going to get? Now, obviously they said they have an investigation, well great -- go investigate, tell us what you have."

Monday's hearing included some searing shots from both sides. Schiff opened by reading a list that included accusations first included in a Trump-Russia dossier of "kompromat" compiled by Steele.

And Republicans fired back with some searing hits of their own -- Reps. Trey Gowdy and Brad Wenstrup asked Comey whether former President Barack Obama was behind leaks involving classified information -- a nod to the "deep state" allegations that the Trump White House has pushed in recent weeks.

The tone even caught the attention of lawmakers on the other side of the Capitol, who chided House investigators.

"I'm concerned when both sides go into kind of a Red Team, Blue team. One thing I can tell you is on the Senate Intelligence Committee, we have been very bipartisan," said Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, on MSNBC's "Morning Joe" Tuesday.

Warner told CNN's Erun Burnett on "OutFront" later Tuesday his committee also needs to speak to Manafort.

"We have to talk to Mr. Manafort," Warner said. "We're going to need to bring him in."

CNN's Eli Watkins contributed to this report.