U.S. President Donald Trump meets with immigration crime victims at the White House in Washington, U.S., June 28, 2017. REUTERS/Yuri Gripas

Michael Bahar, a former top Democratic aide on the House Intelligence Committee, said the panel's investigation into Russian interference in the 2016 election and President Donald Trump's campaign's possible role in it is the "successor to Watergate."

Bahar's comments were published in a Politico report on Saturday, which said that Bahar had had "unparalleled" access to the committee's most sensitive deliberations and inner workings. He recently left the committee to take a job at the law firm Eversheds Sutherland.

Bahar said that although his leave was planned far in advance, he found it difficult to depart because of the Trump-Russia probe's significance at this time.

"This is in a sense having to step aside from history," he said.

A breakdown in bipartisanship

Bahar said the deterioration in the relationship between committee chairman Devin Nunes and ranking member Adam Schiff was difficult to watch for staffers who had taken pride in the intelligence committee's reputation for bipartisanship.

"For those people that had been around the longest, I think there was — I would describe it as sadness through this, because this is not what we're used to," the former staffer told Politico.

Nunes initially spearheaded the House Russia probe but was forced to step aside following his decision to bypass the rest of his committee and brief Trump on classified documents he said showed that members of Trump's transition team had been swept up in government surveillance. Reports have indicated that he received the documents from White House officials.

Following Nunes' departure from the Russia investigation, Republican Rep. Mike Conaway of Texas took over leadership. But because he remains the committee's chairman, Nunes is still somewhat involved in the Russian probe — The Washington Post reported last month that after his recusal, Nunes approved five to six "unmasking" requests to US spy agencies related to Russia's election interference. The Post added that the requests were made with respect to both the Trump campaign and the Hillary Clinton campaign.

House Intelligence Committee Chairman Rep. Devin Nunes, R-Calif. pauses while meeting with reporters outside the White House in Washington, Wednesday, March 22, 2017, following a meeting with President Donald Trump. Pablo Martinez Monsivais/AP

The Post's report drew Nunes into the spotlight once again, and one Democratic committee aide told Business Insider in an earlier interview that Democrats felt the chairman had "gone rogue." The aide added that Nunes and other Republicans on the panel were trying to make unmaskings the focal point of the investigation to divert attention from the growing Trump-Russia controversy.

Bahar, the former Democratic staffer, told Politico that the partisan fraying of relations between panel members had left staffers "shaken." But he added that Conaway's leadership after Nunes' recusal had somewhat mended the problem, saying Conaway was "truly trying to follow the facts wherever they lead."

The question of collusion comes down to one thing

Bahar told Politico that the question of whether members of the Trump campaign colluded with Russia to hand Trump the presidency comes down to intent.

Since the Russia investigations have gained momentum, executive branch officials such as Attorney General Jeff Sessions, former national security adviser Michael Flynn, and senior adviser Jared Kushner have come under scrutiny for their contacts with Russia. Sessions recused himself from any current or future investigations involving the Trump campaign when it emerged that he had failed to disclose contacts he'd had with Russia's ambassador to the US, Sergey Kislyak.

Flynn was forced to resign as national security adviser when it was reported that he had spoken to Kislyak about US sanctions during the presidential transition period and lied to Vice President Mike Pence about it. Former acting attorney general Sally Yates later revealed that she had warned the White House that Flynn could be vulnerable to Russian blackmail weeks before he resigned. Since then, Flynn has increasingly emerged as a central figure in the investigation and he has since been subpoenaed by both the House and Senate intelligence committees. Flynn is also under a separate FBI investigation for failing to register as a foreign agent when he did lobbying work for the Turkish government.

White House Senior Advisor Jared Kushner attends a swearing in ceremony for U.S. Ambassador to Israel David Friedman at the Executive office in Washington, U.S., March 29, 2017. REUTERS/Carlos Barria

Kushner dominated headlines when The Washington Post broke a bombshell report in May which said Kushner had proposed setting up a back channel of communication between Trump and Moscow using Russian facilities. Kushner's reported request alarmed national security experts and former intelligence officials, who were baffled by the request and balked at the suggestion to use Russian facilities.

"We know that there were people who didn’t fully disclose meetings with a foreign power," Bahar told Politico. "We know that there are people who didn’t reveal the sources of their income, foreign sources of their income. Was that because of a lack of memory, inability to fill out forms, disdain for the forms, or was it something else?"

Bahar's assessment has been echoed by legal analysts across the spectrum, and the question of intent has also been raised in the ongoing debate over whether Trump obstructed justice by firing then-FBI director James Comey, who was leading the FBI's own investigation into Russia's election interference and the Trump campaign's possible role in it.

Following Comey's removal, Trump told NBC News' Lester Holt that "this Russia thing" had been a factor in his decision. It later emerged that one day after firing Comey, Trump told Russian officials in an Oval Office meeting that Comey was "a real nut job" and that firing him had taken "great pressure" off of him. The controversy gained steam when Comey revealed, in a memo and later in his testimony to the Senate Intelligence Committee, that Trump had personally asked him to drop the FBI's investigation into Flynn.

Trump's statements don't individually rise to the level of obstruction of justice, said Jens David Ohlin, an associate dean at Cornell Law School and an expert on criminal law. "The obstruction of justice would flow from the entire landscape of Trump's behavior: telling Comey to back off on the Flynn investigation, firing him when he wouldn't, and then admitting on national television that he dismissed Comey because of the Russia investigation," Ohlin said.

Former FBI Director James Comey testifies on Capitol Hill. Drew Angerer/Getty Images

He added that Trump's statement to the Russians in the Oval Office added weight to the inference that Trump used his executive authority to fire Comey to stymie a federal investigation. "His statement to the Russians is indirect evidence of Trump's corrupt intent when he fired Comey," Ohlin said. "It's very significant in that regard."

Overall, however, legal experts agree that intent is difficult to prove, both in Trump's case and in the case of his campaign advisers and executive branch officials. And it's likely the question won't be answered anytime soon.

"I know there's a perception that things sort of stopped," Bahar told Politico, referring to speculation that the House intel committee's investigation stalled after Nunes' recusal. "But to be honest with you, it really didn't, just because there was so much information coming in, so much information to absorb."

He also said the investigation may run into next year. "There are so many tentacles and so many rocks to look under," he said. "And every time you look under another rock, you find some more rocks. I don’t think there’s a quick resolution to this."

In addition to the House and Senate intelligence committees' investigations, the FBI's investigation is also ongoing and led by special counsel Robert Mueller, who was appointed to spearhead the probe following Comey's dismissal.