As the legal battle over President Trump's tax returns rages on, Rep. David Cicilline, D- R.I., Monday argued that Congress should be able to gather all the information possible to conduct oversight, including accessing Trump's financial information.

President Trump made a major move Monday by suing in an attempt to halt a subpoena, issued by the Democratic-led House Oversight Committee, that would compel his accounting firm, Mazars, to reveal his tax returns for the last 10 years.

In the lawsuit, President Trump's lawyer argued that Congress should only be able to view the financial information if there is a legislative purpose. During an appearance on "Outnumbered," Rep. Cicilline, who is also the co-chair of the Democratic Policy and Communications Committee, said that he believes Congress has a right to collect the evidence it sees fit to fulfill its responsibility to conduct oversight.

"I understand that there are some people who think that Congress should not do oversight, and it's kind of rich when the president tries to make himself a victim, as the most powerful man on the planet," Cicilline told host Melissa Francis.

"We are doing our work addressing the economic issues that face the American people, but at the same time, we have to do oversight. I know that that is uncomfortable, but Congress has a responsibility, whatever party, the legislative branch has a responsibility. I know that there are some Trump supporters that think any oversight is unfair, but we have a long tradition of doing oversight, it is part of the responsibility," he added.

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Cicilline went on to discuss the Democrats' new talk of trying to impeach President Trump amid the results of Robert Mueller's investigation. The Democratic representative said he has read the report in its entirety, and that "there was real evidence of the president attempting to interfere with the investigation."

"I think that report is disturbing," Cicilline continued. "It is very damning about the president's conduct. He encouraged people to lie, he encouraged people to not be forthright about events, he himself lied, he attempted to fire the special counsel, he attempted to get Don McGahn to lie about his effort to fire him.

"There is ample evidence of obstruction of justice. It is very clear that the only reason that the president was not charged is that the special counsel concluded that the [Department of Justice] precluded it," he said.

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President Trump maintains that there was no obstruction or collusion on his part, something with which House Democrats vehemently disagree.

Ultimately, Cicilline said, Democrats have more work to do before any further conclusions can be made on the discussion of impeachment.

"There is a process, we will have a series of hearings, which we will take this very seriously, and I think Democrats will continue to be very judicious about it," he said.