On July 27, 2016, in what would turn out to be his last press conference before Election Day, Donald Trump urged Russian hackers to go after Hillary Clinton, specifically the messages she deleted from the private server she used as Secretary of State. “Russia, if you’re listening, I hope you’re able to find the thirty thousand emails that are missing,” he said.

Since then, as the scandal of Russian interference in the election has grown and spread, from a few seemingly unconnected brush fires to a conflagration that could consume his presidency, Trump and his associates have followed a simple rule: deny everything. This week, as the FBI confirmed it is investigating whether there was contact between his campaign and the Russian government, the short-sightedness of that policy became apparent.

Testifying before the House Intelligence Committee, FBI Director James Comey said the agency started digging last July, soon after 22,000 hacked emails from the Democratic National Committee were released by Wikileaks, and that by December it had concluded Russian spies were responsible and that they “wanted to hurt our democracy, hurt her, help him”.

Agents are investigating “whether there was any coordination between the campaign and Russia’s efforts”, Comey said. “As with any counter-intelligence investigation, this will also include an assessment of whether any crimes were committed.”

Trump tried to get ahead of events by tweeting: “This story is FAKE NEWS and everyone knows it!” But now the G-Men are following the smoke trail, it is harder to claim the media started the fire.

In February, when it emerged that national security Adviser Michael Flynn had spoken to the Russian ambassador, Sergey Kislyak, on the day President Barack Obama announced new sanctions against Russia, Trump’s team denied sanctions were discussed. The facts - the truth - showed otherwise and Flynn was forced to resign.

When attorney general Jeff Sessions was asked under oath what he would do if messages between the Trump campaign and Russian diplomats were uncovered, he stated he “did not have communications with the Russians” himself. After two meetings with Kislyak during the campaign came to light, he was obliged to recuse himself from the hacking investigation.

Comey did not name the FBI’s targets, but Trump is already distancing himself from those most likely to be implicated. White House Press Secretary Sean Spicer claimed that Paul Manafort, who was Trump’s campaign manager for five months leading up to the Republican National Convention, "played a very limited role for a very limited amount of time”. Manafort lives in Trump Tower, and was reportedly involved in selecting cabinet members.

The hacking scandal has exposed how deeply partisanship shapes perceptions in this era of extreme polarisation. Like the popular optical illusion that can be seen as a beautiful young woman or a wrinkled old woman, Democrats and Republicans look at the same picture and see two completely different things.

Democrats see a vast conspiracy, stretching back decades, not merely to steal an election but to install a compromised Russian intelligence asset as President of the United States. Republicans see a vast conspiracy between the media, career bureaucrats and intelligence officials – the ‘deep state’ – to undermine Trump’s populist presidency before it can get started.

By increasing the store of known facts and sworn testimony, the FBI investigation will bring one of these images into focus. Senator John McCain has called for an independent, bipartisan committee to be set up, similar to the Select Committee on Presidential Campaign Activities that investigated the Watergate break-in. “No longer does the Congress have credibility to handle this alone," he said.

Was there active collusion between the Trump campaign and Russia’s government? And if there was, did Trump know about it? On Wednesday evening, CNN published a report that hinted at evidence of co-ordination, citing an unnamed law enforcement official: “It appeared they [the Trump team] were giving the thumbs up to release information when it was ready.” The time for anonymous sources has passed. Trump’s opponents need proof.

“I think there needs to be a link that shows Trump was aware of any misdeeds,” says Brian Klaas, Fellow in Global and Comparative Politics at London School of Economics. “If they can show that he was aware then I think that’s game over.”

However, Brown University political science professor Jeff Colgan says even that would not be enough to provoke a full-blown crisis of legitimacy: “It would probably take something beyond the election, in which there’s a real sense Donald Trump and his team were hurting America’s national interests, and not just trying to win an election.”

That Russia put a thumb on the scales is now beyond dispute. Seventeen intelligence agencies have concluded Russian hackers broke in to the DNC server and Clinton campaign chairman John Podesta’s email account. Millions of social media posts linking to right wing news sites and attacking Clinton were generated by ‘bots’ the FBI suspects to be of Russian origin.

Congressman Adam Schiff, the leading Democrat on the House Intelligence Committee, has said there is “more than circumstantial evidence” that Trump’s staff knew about and encouraged this intervention.

The connected stories of Trump’s deep ties to Russia and Russian interference in the election have all the ingredients of a lurid spy thriller, but Democrats would be wise to concentrate on what they can prove. The rogue’s gallery of Trump’s Russian acquaintances – among them convicted racketeer Felix Sater and Anatoly Golubchuk, who ran an illegal gambling den in Trump Tower – makes for good tabloid copy and little else.

That Russian diplomats Sergei Krivov, Oleg Erovinkin and Vitaly Churkin have all died in mysterious circumstances since the election may eventually turn out to be relevant, but for now it is a distraction. Even the notorious Steele dossier, with its allegation of a blackmail tape featuring Trump and Russian prostitutes (among other much more solid, substantiated claims) has thus far proven to be a double-edged sword, rather than the ‘smoking gun’ Democrats are so desperately hoping to find.

On Tuesday, the Associated Press published a story showing that Manafort’s ties to the Putin regime are more direct than previously suggested by his work for pro-Russia Ukrainian billionaire Dmytro Firtash. In a 2005 memo to oligarch Oleg Deripaska, Manafort offered to provide services that would “greatly benefit the Putin Government”. He insists the $10 million he was paid, through a shell company registered in Delaware, was for lobbying and nothing more.

On left-wing sites, this was a bombshell. On Fox News, it appeared near the bottom of the page, beneath stories about a cinema providing sick bags with tickets for a horror movie, and a Wheel of Fortune contestant that hadn’t heard of A Streetcar Named Desire.

“To a lot of people, it’s just noise,” says Yale Political Science Professor Nick Robinson. “Pulling it back to say that Trump knew or authorised it is something that Democrats need to be careful about, in terms of setting expectations.” In a poll published this week by the McCourtney Institute of Democracy, just 3% of the Trump supporters surveyed said they regret their vote.

Republican attitudes to Putin have changed sharply in the last two years. In July 2014, 51% of the Republicans surveyed by YouGov viewed the Russian President “very unfavourably”. By December 2016 only 14% held such a negative opinion of him.

Trump has been praising Russia’s “strong leader” for doing a “great job” since 2007. In 2013, when Moscow hosted the Miss Universe pageant, Trump wondered “will [Putin] become my new best friend?” His uncritical embrace of Putin during the campaign explains part of the changing GOP sentiment.

But there is also a deeper shift, driven by Evangelicals who see Putin’s backward-looking, ethnically homogenous Russia as a beacon of Christian values. “Putin has done a better job of rebranding Russia as the standard-bearer for so-called traditional values conservatism,” says Christopher Stroop, a historian at the University of South Florida. “The right got the message, which was directed at them: Russia is a right wing state now.”

On a trip to Moscow in 2015, Evangelical leader Franklin Graham praised Putin for “protecting Russian young people against homosexual propaganda”. Last month, Brian Brown, founder of the National Organisation for Marriage, travelled to the Russian capital to express the “strong common bond with these countries of reverence and appreciation for the natural family”.

Conservative commentators have sought to frame the investigation as a leftist plot. “The more hysterical liberals become about Russia, the more your antennae should go up,” wrote hard right columnist Ann Coulter. “The No. 1 enemy of Western civilisation today isn't non-communist Russia. It's Islam. And who is a key ally in that fight? Russia has been dealing with these troublesome Muslims for centuries.”

Stroop says: “Right after the election, when the charge was being levelled that there was a Russian influence campaign, Franklin Graham took to Twitter and tweeted that ‘no, it was God who influenced this election; it wasn’t the Russians.”

On Wednesday, Republican Congressman Devin Nunes, chair of the House Intelligence Committee, announced that “the intelligence community incidentally collected information about US citizens involved in the Trump transition”. This brazen attempt to back up Trump’s claim that Obama wiretapped his office (an allegation comprehensively debunked by the FBI, NSA, and British intelligence) inadvertently revealed that members of the campaign were in contact with foreign nationals under surveillance.

The Nunes comments point towards an individual, or individuals, targeted by American intelligence - perhaps a Russian agent, who knows? - who happened to be communicating with members of the Trump transition team. 'Incidental' is the key word - Trump was not the target. His boosters Sean Hannity, Bill O’Reilly and Rush Limbaugh naturally reported that the President had been vindicated, but the Wall Street Journal editorial page, a leading conservative voice, accused Trump of clinging to his unfounded assertion “like a drunk to an empty gin bottle”.

Nunes told the White House about the incidental collection before Schiff, his Democratic colleague on the Intelligence Committee. “In a criminal trial, you don’t have new evidence that the judge rushes to the defendant, and in the same way, an oversight committee… cannot go directly to the person being investigated,” says Klaas. “It backfired because John McCain is now calling for a select committee, which is the last thing Trump wants.”

Robinson agrees: “I think the bigger question here is demands for a special prosecutor. That has a lot of power because then they interview people under oath. In Watergate, most people were not convicted of anything that they did in the scandal - they got convicted for perjury and obstruction of justice, trying to cover up things after the fact.”

On Wednesday, Supreme Court nominee Neil Gorsuch completed his Senate confirmation hearing, and although Democrats have threatened to filibuster his appointment, looks set to be confirmed before too long. On Thursday and Friday, Congressional Republicans scrambled to find the votes they need to sign the American Health Care Act into law (ultimately falling short, for the time being).

In the middle of this vital week for his administration, the President could not resist a little TV criticism. “Just watched the totally biased and fake news reports of the so-called Russia story on NBC and ABC,” he tweeted. “Such dishonesty!”

“It is going to cast a shadow over everything he does, and that shadow is getting longer every time he tweets about it,” says Klaas. “I think it’s going to plague his legislative agenda until that report comes out that either implicates him or exonerates him.”

“In terms of getting people to change their vote, I think Russia is not one of the main issues,” says Colgan. “But the second issue is the erosion of democracy itself here in the United States. And that issue goes beyond the next election. It goes beyond partisan politics. And Democrats are right to be saying ‘this is not about party, this is about country, and people should be up in arms about it’.”