The chairman of the House Oversight and Government Reform Committee Monday demanded that President Obama dump IRS boss John Koskinen immediately, threatening to impeach the agency boss if the president refuses.

"It is time for the president to remove Mr. Koskinen," said Rep. Jason Chaffetz, chairman of the influential panel that believes the IRS chief has lied to the panel and orchestrated an evidence destruction project.

Chaffetz added: "It is imperative that this committee pursue all constitutional remedies, that may include contempt and it may even include impeachment of Mr. Koskinen. We take this matter very seriously. We have not resolved this. The president has not lived up to his obligations."

The top Democrat on the panel, however, dismissed the attack on Koskinen as a "strange, oddly-timed rehashing of conspiracy theories."

At a press conference, Chaffetz said that he sent the president a 30-page letter detailing the committee's concerns with the IRS, which were also portrayed in an unusual, video.

The GOP video is a remarkable accounting of years of IRS efforts, starting with Lois Lerner, the ex-official who led the targeting of conservative and Tea Party foes of Obama, to duck demands for emails and other documents.

It also details multiple efforts by IRS to destroy key evidence after "non-destruction" demands were issued, and the agency's bid to avoid searching for subpoenaed documentation that should have been easy to find. Koskinen is portrayed as an agency leader who publicly offers to help the committee, but privately stonewalls.

The 10-and-a-half minute YouTube concludes:

"The bottom line. IRS didn't fulfill their legal responsibility to respond to Congress. They didn't preserve information. They didn't try to find the information. They misled Congress for years. Their failings leave the American people in the dark about how their First Amendment rights were trampled upon. There must be accountability."

The GOP call on Obama was dismissed by the top Democrat on the House panel, Maryland Rep. Elijah E. Cummings.

In a statement, he mocked the video and said that it included "no new information" and dismissed the calls for Koskinen to be fired.

"The bottom-line is that the Inspector General found no evidence to back-up Republican claims of political motivation, White House involvement, or intentional destruction of evidence. Calls for Commissioner Koskinen to step down are nothing more than a manufactured Republican political crisis based on allegations that have already been debunked," said Cummings.

Last week, speaking to the moderate Republican Ripon Society, the Utah Republican said that documents received by the committee and others in Congress prove the IRS politically targeted conservative groups, blocking them from receiving tax-advantaged status that they deserved.

"You have political targeting that is factual at this point. There are no ifs, ands or buts. You had groups within the IRS who were politically targeting conservatives and impeding their First Amendment rights," he said last week, adding, "I promise you – there will be news on the IRS side as early as next week. So stay tuned."

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.