(CNN) In the chaotic aftermath at the FBI following Director James Comey's firing, a half-dozen senior FBI officials huddled to set in motion the momentous move to open an investigation into President Donald Trump that included trying to understand why he was acting in ways that seemed to benefit Russia.

They debated a range of possibilities, according to portions of transcripts of two FBI officials' closed-door congressional interviews obtained by CNN. On one end was the idea that Trump fired Comey at the behest of Russia. On the other was the possibility that Trump didn't have an improper relationship with the Kremlin and was acting within the bounds of his executive authority, the transcripts show.

James Baker, then-FBI general counsel, said the FBI officials were contemplating with regard to Russia whether Trump was "acting at the behest of and somehow following directions, somehow executing their will."

"That was one extreme. The other extreme is that the President is completely innocent, and we discussed that too," Baker told House investigators last year. "There's a range of things this could possibly be. We need to investigate, because we don't know whether, you know, the worst-case scenario is possibly true or the President is totally innocent and we need to get this thing over with — and so he can move forward with his agenda."

Following Comey's firing, the FBI opened a probe into Trump for possible obstruction of justice , as CNN has previously reported. Part of the impetus for the investigation, the New York Times first reported Friday, was whether Trump's actions seemed to benefit Russia.

The congressional transcripts obtained by CNN reveal new details into how the FBI launched the investigation into Trump and the discussions that were going on inside the bureau during a tumultuous and pivotal period ahead of the internal investigation and special counsel Robert Mueller's appointment.

Republicans view the officials' comments as evidence that top officials at the FBI were planning all along to investigate Trump and that the probe wasn't sparked by the Comey firing, according to a Republican source with knowledge of the interviews.

While the FBI launched its investigation in the days after Comey's abrupt dismissal, the bureau had previously contemplated such a step, according to testimony from former FBI lawyer Lisa Page.

Peter Strzok, the former FBI agent who was dismissed from Mueller's team and later fired over anti-Trump text messages, texted Page in the hours after Comey's firing and said: "We need to open the case we've been waiting on now while Andy is acting," a reference to then-acting FBI Director Andrew McCabe.

Page was pressed on the meaning of the message in her interview with congressional investigators, and she confirmed that the text was related to the Russia investigation into potential collusion.

Page told lawmakers the decision to open the case was not about "who was occupying the director's chair," according to a source. While FBI lawyers limited her answers about the text, she said the text wasn't suggesting that the case couldn't be opened with Comey as director.

"It's not that it could not have been done," Page told lawmakers. "This case had been a topic of discussion for some time. The 'waiting on' was an indecision and a cautiousness on the part of the bureau with respect to what to do and whether there was sufficient predication to open."

Portions of Page's interview were first reported by The Epoch Times.

This weekend, Trump in a series of tweets attacked the FBI and Comey, calling him a "crooked cop."

"Wow, just learned in the Failing New York Times that the corrupt former leaders of the FBI, almost all fired or forced to leave the agency for some very bad reasons, opened up an investigation on me, for no reason & with no proof, after I fired Lyin' James Comey, a total sleaze!" Trump tweeted

In his congressional testimony, Baker said that he did not discuss with Comey the possibility that Russia had influenced his firing. But Baker met with a group of roughly a half-dozen officials, including McCabe and possibly Strzok and Page, to discuss it.

"Not only would it be an issue of obstructing an investigation, but the obstruction itself would hurt our ability to figure out what the Russians had done, and that is what would be the threat to national security," Baker told lawmakers, according to an excerpt from the transcript first reported by the Times and confirmed by CNN.

Baker said the notion that Trump was acting at the behest of Russia was "discussed as a theoretical possibility."

"I'm speaking theoretically. If the President of the United States fired Jim Comey at the behest of the Russian government, that would be unlawful and unconstitutional," Baker said.

"Is that what happened here?" Rep. John Ratcliffe, a Texas Republican, asked Baker.

"I don't know," Baker responded, before the FBI lawyer cut off additional questions on that line of inquiry.

Representatives for Baker, Page, Strzok and McCabe declined to comment.

Comey's firing wasn't the only development that prompted the investigation into Trump, according to the Times, as Trump subsequently tied Comey's firing to the Russia investigation on two separate occasions before the investigation was launched, including in an NBC News interview two days after Comey's dismissal.

Republicans asked in their interviews with FBI officials questions about the fact that both Comey and McCabe kept memos detailing their conversations with Trump, a step they didn't take with President Barack Obama. Comey's memos, in which he wrote that Trump suggested Comey drop the probe into former national security adviser Michael Flynn, were leaked by a friend of Comey after his firing in an effort to spark the appointment of a special counsel.

When Page was asked about McCabe's memos, she acknowledged she had reviewed some of them, though she said it was mostly for proofreading. House Republicans issued a subpoena for McCabe's memos last year, but the Justice Department did not hand them over, according to a source familiar with the congressional investigation.

In his interview with House investigators, Comey was pressed on why he made memos of his conversations with Trump about an ongoing investigation, but not Obama. Comey responded that Obama discussed the Hillary Clinton email investigation "on Fox News" and he didn't need to memorialize such a public comment.

"The public comments, because they were widely broadcast, were ones that were apparent to the senior leadership team of the FBI," Comey said. "If I didn't tell the senior leadership team of the FBI about my conversation with President Trump, they wouldn't otherwise know and couldn't help me figure out what to do with what was potential obstruction of justice."

The FBI officials were interviewed as part of the Republican House investigation into the FBI's conduct in the Clinton and Trump investigations, which ended after Democrats took control of the House this month.