First came the lie. Then came the cover-up. It’s a classic Washington two-step. And the news that Michael Flynn, a former White House national security adviser, has pleaded guilty to perjury means Donald Trump may soon be dancing to the tune of the special counsel investigating the accelerating Russian influence-peddling scandal.

Flynn’s guilty plea rained a cold shower on Trump’s victory parade celebrating a rare success in Congress. After 10 months watching his healthcare plan and other ill-conceived policies being shot down in flames, Trump finally managed to get his tax cuts bill through the Senate late on Friday night.

Little matter that the tax changes, which will benefit the richest Americans and big corporations, betray the blue-collar voters who put him in office. Little matter they will add an estimated $1.2tn to the already bloated federal deficit. A win’s a win in Trump’s zero-sum book.

But the Flynn affair is a different matter altogether. A former general sacked by Barack Obama, Flynn was best known, until now, for his ferocious attacks on Hillary Clinton before last year’s election. He famously led a chant of “Lock her up” at a Republican party rally. . Now it is Flynn who is staring jail in the face.

By admitting he lied to the FBI when he had denied holding secret talks last December with the Russian ambassador Sergey Kislyak to illegally subvert Obama administration policy, Flynn has raised the lid on a possible illegal conspiracy reaching all the way to the top.

Last night Trump said Flynn’s actions had been “lawful” and said on Twitter that he had fired him “because he lied to the vice president and the FBI”.

Jared Kushner, Trump’s son-in-law, Jeff Sessions, the attorney general, and several other campaign and transition officials have all denied personal contact, or knowledge of contacts, with the Russians before Trump took office in January. Yet Flynn’s sworn evidence states he either discussed or took orders about his meetings with senior figures in Trump’s team.

Kushner was reportedly one of those senior figures. Others in the frame include Donald Trump Jr (Trump’s eldest son), Michael Cohen, a lawyer, and Carter Page, a campaign adviser. Another adviser, George Papadopoulos, recently pleaded guilty to lying to investigators. Trump himself has publicly and repeatedly denied prior knowledge of the contacts with the Russians. The future of his presidency now hinges on the veracity of those statements.

Kushner, a close confidant inside the family circle, is plainly in the sights of the special counsel, Robert Mueller. Trump named Kushner his senior adviser on Middle East policy last January. Prosecutors say that, in the previous month, Flynn was directed by a “very senior member” of the Trump team to ask the Russians to help oppose a UN resolution unfavourable to Israel, contrary to Obama’s policy at the time.

The unfriendly relationship between Benjamin Netanyahu, Israel’s rightwing prime minister, and Obama is a matter of record. So, too, are Kushner’s pro-Israel stance and his personal links to Netanyahu, a close family friend who once slept in Kushner’s childhood bedroom in New Jersey.

Other people who now occupy top posts in the administration have questions to answer. The transition team was led by Mike Pence, the vice-president.

Trump and Pence claimed in February to have been misled by Flynn about his contacts with Kislyak concerning Obama’s imposition of sanctions on Moscow for election meddling. Yet court documents relating to Flynn’s guilty plea say multiple members of the transition team coordinated with Flynn to ask Russia not to retaliate.

In the event Vladimir Putin, Russia’s president, did not take retaliatory action, which was in itself unusual. The day after Flynn met Kislyak, Trump tweeted from his Mar-a-Lago resort in Florida that Putin was “very smart” not to hit back. The tweet was retweeted by the Russian embassy.

Kislyak has since been recalled and elevated to senatorial rank in Russia’s upper house of parliament.

After Trump sacked Flynn in February for supposedly misleading him and Pence, he asked James Comey, the FBI director, whether he could “see your way clear to letting this go, letting Flynn go”, according to Comey’s testimony to Congress. Comey refused. His subsequent sacking by Trump led directly to the special counsel’s appointment.

In addition to the alleged Russia conspiracy, Mueller is now investigating whether Trump’s firing of Comey and Flynn was part of an attempted cover-up to conceal the original lie. That would constitute obstruction of justice – a charge of sufficient gravity that, if proved, could spell the end for Trump.