House Speaker Nancy Pelosi on Sunday issued what amounts to an ultimatum to President Donald Trump: Come clean about the Ukraine scandal, or the House will move to impeach you.

It will come to a head on Thursday, when the Acting Director of National Intelligence, Joseph Maguire, is scheduled to testify on Capitol Hill.

Pelosi’s demand is that Maguire must hand over the complaint from the whistle blower in this case, as the law explicitly requires, or the administration “will be entering a grave new chapter of lawlessness which will take us into a whole new stage of investigation.”

Pelosi has resisted calls to impeach Trump until now, but she clearly appreciates the gravity of this one. In a rambling answer to reporters’ questions, Trump seemed to acknowledge that he asked the president of Ukraine to investigate Hunter Biden, the son of the former vice-president, who did business in Ukraine while his father was vice-president.

Why is that so bad? Because if it’s true, Trump was soliciting a foreign power to intervene in our election. Because the demand came while the White House was withholding $391 million in aid to Ukraine, undermining a small country’s ability to fend off Russian violence, which has clear impact on our national security. And because the law states that the administration “shall” share whistle blower complaints with Congress, once they are determined to be “credible” and “urgent” by the inspector general, as in this case.

On each count, the alleged conduct is even worse than Trump’s behavior towards the Russians during the 2016 election, when he openly welcomed help from Vladimir Putin’s government, according to the report from special counsel Robert Mueller. In that case, Mueller found insufficient evidence to charge Trump with the explicit collusion alleged in the Ukraine case.

“This is much worse,” says Rep. Tom Malinowski, D-7th. “This is the president of the United States using the powers of the presidency to compel a foreign government to help him politically, and he’s basically admitted it.”

Keep in mind, the inspector general who found the whistle blower’s complaint to be urgent and credible, Michael Atkinson, was appointed by President Trump. He wrote that the complaint “relates to one of the most significant and important of the Director of National Intelligence’s responsibilities to the American people."

This is no deep state conspiracy by holdovers from the Obama era. This is what it sounds like when a person who believes in the rule of law bangs an alarm.

If the White House refuses to share this complaint with Congress, that is the definition of a cover-up. It would be the morale equivalent of Richard Nixon burning the White House tapes, a clear abuse of power that, on its own, would justify Trump’s impeachment and removal from office. If Congress accepts that defiance, then it will be complicit in Trump’s misrule and degradation of the rule of law.

As for Biden, father and son, it is difficult to parse the accusation against them because no one has made an explicit charge. We know that Biden, as vice president, pressed Ukraine to fire its chief prosecutor, Viktor Shokin, as did many other Western leaders, along with the International Monetary Fund, who all felt he was not fighting corruption with the needed vigor. Shokin had previously investigated a Ukrainian natural gas company that had added Hunter Biden to its board, but that investigation had been shelved by the time Joe Biden acted.

If there is evidence that either Biden broke American law, then the FBI should investigate, by all means. But so far there is nothing but smoke, from the guy who claimed for years that he had proof President Obama was born in Kenya.

Trump now says he may release the transcript of the call, and some of his supporters say his request for an investigation of Biden would be legitimate, so long as there was no promise of punishment or reward in response, a quid pro quo.

Nonsense. When a small country facing Russian aggression is denied $391 million in aid by a president who then asks for a favor, the implicit threat is obvious. Sen. Chris Murphy, D-Conn., visited Kiev earlier this month, and said the Ukrainian president was concerned that the aid was frozen as a “consequence” of his unwillingness to launch a politically motivated investigation into the Bidens.

Malinowski puts it this way: “If a bunch of mafia enforcers kidnap your family, and then a couple of days later ask for a loan, does he really have to say, ‘Or else you’ll never see your family again?’”

Thursday could be a big day in American history. If Trump doubles down on this cover up, then the only way to vindicate the rule of law is to impeach him.

More: Tom Moran columns

Tom Moran may be reached at tmoran@starledger.com or call (973) 836-4909. Follow him on Twitter @tomamoran. Find NJ.com Opinion on Facebook.