Julian Zelizer is a professor of history and public affairs at Princeton University, and author, with Kevin Kruse, of the new book "Fault Lines: A History of the United States Since 1974." The opinions expressed in this commentary are his own. View more opinion at CNN.

(CNN) I ran into a senior Democrat in the US House of Representatives while traveling Thursday night. After introducing myself and telling this member about my work as a political analyst and historian, this person asked me the question that seems to be on almost everyone's mind: Is it time to impeach President Donald Trump?

The answer to that question is changing by the minute.

A few hours after this encounter, BuzzFeed published a shocking story alleging that Trump instructed his former fixer Michael Cohen to lie to Congress about the Moscow Trump Tower, a real estate deal that was being discussed during the 2016 campaign. According to the story, Ivanka Trump and Donald Trump Jr. had been regularly updated on the project as well. A spokesman for Ivanka Trump's ethics counsel Abbe Lowell has made a statement emphasizing that Ms. Trump was "only minimally involved" in the project.

CNN has not independently confirmed the BuzzFeed story. And in an unusual move Friday evening, a spokesman for Special Counsel Robert Mueller said, "BuzzFeed's description of specific statements to the Special Counsel's Office, and characterization of documents and testimony obtained by this office, regarding Michael Cohen's Congressional testimony are not accurate."

BuzzFeed responded with its own statement standing behind the report. If the BuzzFeed story is true, the news will be devastating. Both Presidents Nixon and Clinton were charged as part of their impeachment proceedings for coaching witnesses to make false testimony.

Until recently, the voices calling for impeachment proceedings have been limited. Billionaire Tom Steyer has conducted a one-man advertising campaign to make the case and build political support for impeachment. There have also been a few Democrats in the House beating the drums that the time has come to start this process. Still, when first-term legislator Rashida Tlaib said, "We're going to impeach the m*****f****r!" there was an uproar -- and not just about her choice of words.

But the momentum toward impeachment appears to be growing at a rapid pace. Former attorney general Eric Holder tweeted that if the BuzzFeed story is true, "Congress must begin impeachment proceedings." On the cover story of the next Atlantic, Yoni Appelbaum outlines one of the most powerful cases thus far as to why we need impeachment proceedings now and how they have been extremely valuable at previous moments in American history.

Ben Sherman, a Democrat from California, re-introduced articles of impeachment earlier this month. Congressman Jerry Nadler, the chairman of the House Judiciary Committee, said that his committee will investigate in response to the BuzzFeed story.

JUST WATCHED Giuliani: BuzzFeed story is "categorically false" Replay More Videos ... MUST WATCH Giuliani: BuzzFeed story is "categorically false" 03:34

In other words, the tide feels as if it might be turning.

There are many good reasons for House Democrats to start this process now. The most important is that Congress needs to provide some kind of public accounting for what this President might or might not have done. Because the Republican Congress dropped the ball in conducting serious public hearings into the election, the potential obstruction, and all of the other accusations swirling around this administration, most of the investigative legwork has been completed by news reporters and Robert Mueller's legal team. The result is that much of the information-gathering has been done in secret.

It is now time for Congress, the institution that will ultimately determine whether the President has committed high crimes and misdemeanors, to launch its own proceedings. Congress cannot rely on the Department of Justice to handle this job alone. The House can either first turn to relevant committees to conduct hearings of their own before turning the matter over to Judiciary. Or, as occurred under Peter Rodino in 1974, the House Judiciary Committee could conduct an investigation of its own by assembling a first-rate team of lawyers and calling witnesses. The Judiciary Committee can then make a determination as to whether the weight of evidence moves them to vote for articles of impeachment.

Political considerations should not dictate what House Speaker Nancy Pelosi decides to do. There are moments in American political history when congressional leaders have the obligation to do the right thing regardless of the potential political costs. Given the body of very serious charges that are now facing this President, it would be almost reckless for the House to refrain from investigating.

The cumulative allegations now range from the President being an agent of -- or beholden to -- a foreign government after working with it to win election, to his making foreign policy decisions based on his family's personal financial interests.

While House Republicans did not handle the Bill Clinton investigation well in 1998, and they allowed their partisan interests to overwhelm sound deliberations; House Democrats offer a different historical model from 1974, when the House Judiciary Committee recommended the impeachment of Richard Nixon. In that case, they conducted their hearing and their vote in a sound manner, gradually achieving bipartisan support, and produced an outcome -- voting in favor of several articles of impeachment -- that few historians look back on as a mistake.

None of the usual objections to an impeachment process currently hold. The standard argument that an impeachment proceeding would "distract" the President from the serious business of governing isn't really relevant right now, because the federal government is not up and running. It is impossible to predict the political consequences of an impeachment process, but after President Nixon resigned, Democrats won huge majorities in the 1974 midterms and the presidency in 1976.

Finally, the current state of Washington should be a rather stark reminder to Democrats and Republicans of the dangers the nation faces right now with the status quo of a dysfunctional White House. President Trump has proven repeatedly that he already is not handling the basic components of the job.

We have become accustomed to the unconventional developments of this White House, but the current national emergency should be a turning point.

Congress needs to recognize that the presidency is in the hands of someone who is incapable of keeping the government functioning. The responsibility for the shutdown is all his. Democrats and Republicans agreed to a short-term budget that did not include a border wall. He insisted on a border wall and is holding the government hostage until he gets it.

As House Democrats contemplate whether to trigger an impeachment proceeding, the current state of affairs should be part of how they think about their decision, given that they are dealing with a President who doesn't seem like he can or wants to handle his responsibilities.

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So the answer to the legislator's question to me Thursday night is getting pretty close to an affirmative, yes. Not that President Trump should be impeached, but we do need to start the process. The facts in front of us are making the logic of the House starting an impeachment investigation almost inevitable.

This article has been updated with the special counsel's statement on the BuzzFeed story.