What is the true nature of Trump’s relationship with Russia? The story could not be bigger or the stakes higher, but much is still obscured from view

“It’s bigger than Watergate.” “It’s a transparent sham.” “It’s a constitutional crisis.” “It’s a legal cliffhanger.”

Whatever else it may be, the story of Donald Trump and Russia comes down to this: a sitting president or his campaign is suspected of having coordinated with a foreign country to manipulate a US election. Trump strongly denies all wrongdoing and calls the inquiry a “witch hunt”. But prosecutors see red flags everywhere.

The story could not be bigger, and the stakes for Trump – and the country – could not be higher.

Investigators are asking two basic questions: did Trump’s presidential campaign collude at any level with Russian operatives to sway the 2016 US presidential election? And did Trump or others break the law to throw investigators off the trail?

The revelation Monday that a former Trump foreign policy adviser, George Papadopoulos, was informed in April 2016 by a Russian contact that Moscow had obtained “thousands of emails” containing “dirt” on Hillary Clinton has made the question of collusion more urgent. Prosecutors are investigating how far the discussion between the two sides of “dirt” on Clinton went, and what, if any, action was taken.

Separately Monday, former Trump campaign chairman Paul Manafort turned himself in to federal authorities to face charges including conspiracy against the United States, tax evasion and money laundering. Beginning in 2005, Manafort worked as a political consultant and business partner with Russian oligarchs and Kremlin-linked politicians in Ukraine, as did his colleague Richard Gates III, who was also indicted on Monday.

Play Video 0:32 Paul Manafort seen entering FBI field office in Washington DC – video

Manafort joined the Trump campaign in March 2016 and resigned in August after his ties to Kremlin-linked figures came under increasing scrutiny.

The charges against Manafort are separate from but related to the allegations of “collusion” between the Trump campaign writ large and Russian operatives. The presence at the top of the campaign of a suspect accused of working in secret for a foreign government, and of hiding money in offshore accounts to avoid tax payments, places the campaign uncomfortably close to Kremlin interests.

But the charges against Manafort and Gates do not mention any attempted manipulation of the 2016 election. Though Manafort personally offered “private briefings” on the election to the Russian oligarch Oleg Deripaska in July 2016, Trump has denied any knowledge of Manafort’s dealings in the former Soviet bloc and has defended Manafort as a “very decent man”.

While a majority of the American public now believes that Russia tried to disrupt the US election, opinions about Trump campaign involvement tend to split along partisan lines: 73% of Republicans, but only 13% of Democrats, believe Trump did “nothing wrong” in his dealings with Russia and its president, Vladimir Putin.

The affair has the potential to eject Trump from office. Experienced legal observers believe that prosecutors are investigating whether Trump committed an obstruction of justice. Both Richard Nixon and Bill Clinton – the only presidents to face impeachment proceedings in the last century – were accused of obstruction of justice.

Facebook Twitter Pinterest Trump’s firing of the FBI director James Comey, shown here on 8 June 2017 as he testified before the Senate select committee on intelligence, could be an obstruction of justice. Photograph: J. Scott Applewhite/AP

But Trump’s fate is probably up to the voters. Even if strong evidence of wrongdoing by him or his cohort emerged, a Republican congressional majority would probably block any action to remove him from office. (Such an action would be a historical rarity.)

Deepening negative perceptions attached to the Russia affair could, however, be the force that levels Trump, dooming a 2020 re-election bid. Or the president may yet be fully vindicated, re-elected and elevated in the eyes of the people.

None of the three congressional committees investigating the matter, nor the special counsel, Robert Mueller, has yet announced any evidence of collusion between the Trump campaign and Russian operatives. The investigations have an open timeline.

Here’s what you need to know:

What are the most serious allegations?

It appears that prosecutors are weighing serious charges, including obstruction of justice, against Trump. (Weighing a charge does not mean bringing a charge.) Current and former Trump aides are likewise under intense pressure, a point underscored by the arrest of Paul Manafort and Richard Gates on 30 October and by George Papadopoulos’s guilty plea.

Collusion. Did Trump or his campaign “collude” with Russia to tip the 2016 election? Such collusion could take many conceivable forms. Investigators might be looking into whether members of Trump’s digital team traded information with Russia-linked hackers about which voters the campaign was most interested in. Or they might be looking for evidence of conversations about the timing of the release of certain hacked materials. Or they could be seeking information about potential hacking targets. (No evidence has yet emerged of any of the above; Trump and his aides have denied all wrongdoing.)

Obstruction of justice. Has Trump gotten in the way of law enforcement efforts to figure out what happened? Investigators might be looking into whether Trump intended, by firing the FBI director James Comey on 9 May 2017, to pull the plug on the Russia investigation. Trump seems to have admitted as much. “I just fired the head of the FBI,” Trump reportedly told Russians in the Oval Office the next day. “He was crazy, a real nut job. I faced great pressure because of Russia. That’s taken off.”

Facebook Twitter Pinterest Trump jokes with the Russian foreign minister, Sergei Lavrov, and the Russian ambassador to the US, Sergey Kislyak, during a meeting at the White House, a day after firing the FBI director James Comey. Photograph: HO/AFP/Getty Images

But Trump’s frame of mind is crucial in weighing a potential obstruction charge, and he has offered alternative explanations for the firing of Comey, including that Comey was mismanaging the FBI. To discern Trump’s intent, investigators are probably focusing on an initial letter to fire Comey drafted by Trump but rejected by the White House counsel. That letter has not yet been made public.

Abuse of power. Trump may have committed offenses that relate specifically to the office of the presidency, such as a violation of the oath of office (to uphold the constitution), or an abuse of power, which might, for example involve, firing Comey out of personal pique at Comey’s refusal publicly to say that Trump was not personally a target of the Russia investigation.

We don’t for the moment know, however, what exactly the investigators – three congressional committees plus the special counsel – are investigating. The official order appointing Robert Mueller authorizes him to investigate “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump” and related matters. Mueller is authorized to prosecute federal crimes.

Current and former aides. Trump aides are thought to face potential charges including money laundering, making false statements, failure to register as foreign agents, campaign finance violations and more. In May, the former national security adviser Michael Flynn invoked constitutional protections against self-incrimination to avoid testifying before a Senate committee. Paul Manafort was arrested on 30 October on money laundering, tax evasion and conspiracy charges. On the same day it was revealed that foreign policy adviser had pleaded guilty to making false statements to the FBI. Trump’s son-in-law Jared Kushner stood outside the White House that month and said: “I did not collude.” The former campaign aides Carter Page and Roger Stone have both been questioned by investigators and asked to turn over documents and records. The attorney general, Jeff Sessions, has defended himself against accusations of making misleading statements to Congress. All these men – Flynn, Manafort, Kushner, Page, Stone and Sessions – have denied wrongdoing.

How much trouble is Trump in?

Congress. The short answer to this question is another question: who controls Congress? As long as Republicans are in charge, Trump is not likely to face impeachment proceedings or to be removed from office. A two-thirds majority in the Senate is required to remove a president from office through impeachment. Before such action, a simple House majority would be required to pass articles of impeachment.

Public opinion. If public opinion swings precipitously against the president, however, his grip on power could slip. At some point, Republicans in Congress may, if their constituents will it, turn on Trump.

Criminal charges. Apart from impeachment, Trump could, perhaps, face criminal charges, which would (theoretically) play out in the court system as opposed to Congress. Mueller has the power to file criminal charges against Trump, but it’s a matter of debate among scholars and prosecutors whether Trump, as a sitting president, may be prosecuted. It’s never been tried before.

Losing re-election. The most likely price Trump would pay, if he were perceived as guilty of wrongdoing, would be a 2020 re-election loss. Every president to win re-election since the second world war did so with an approval rating in the 49% or 50% range or better. Trump’s average approval rating is in the mid-to-upper 30s. The number could slide even further if, for example, one of his former aides or cabinet members is indicted on money laundering charges.

Is this a ‘witch hunt’ as Trump claims?

“You are witnessing the single greatest WITCH HUNT in American political history – led by some very bad and conflicted people! #MAGA” Trump tweeted in June. Elsewhere, Trump has decried what he says are the wasteful costs of investigating the case.

Donald J. Trump (@realDonaldTrump) You are witnessing the single greatest WITCH HUNT in American political history - led by some very bad and conflicted people! #MAGA

Those assertions would seem to be undercut by developments such as the arrest of Manafort and Papadopoulos’s guilty plea. But many factors go into judging the value of the investigation.

Partisan split. Are the president and his team the victims of a witch-hunt? Your answer to the question probably depends on your political affiliation.

Seventy-three per cent of registered Republicans think Trump did “nothing wrong” in his dealings with Russia and Putin, according to a Marist poll in July. But only a 36% minority of US adults overall think Trump did “nothing wrong”, the poll found. Forty-one per cent of Democrats said they thought Trump had done “something illegal” and 59% said Trump’s campaign associates had broken the law.

Record of conduct. Apart from public opinion, what do we have to go on? A record of conduct by Trump and his aides going back decades, which is defined by secrecy and denials.

Trump has denied his past links to Russian investors and partners and a long history of attempted business deals in Russia, while praising Putin. Trump aides denied the occurrence of meetings and conversations with Russian operatives that came to light anyway. When a June 2016 Trump Tower meeting was revealed, Trump misled the public as to its purpose. His tax returns, which could reveal previously undisclosed financial relationships, remain sealed to the public.

Faith in the rule of law. Is this a witch-hunt? A negative reply relies on a faith in the rule of law in the United States.

Have investigators proceeded logically, in response to a reasonable suspicion of wrongdoing, and in accordance with congressional and justice department guidelines?

Republicans in Congress have given the allegations against the Trump campaign sufficient credence to advance investigations in three committees. Trump’s own justice department saw fit to take the step of appointing Mueller.

Facebook Twitter Pinterest Robert Mueller took over the high-stakes Russia probe in May after US President Donald Trump fired James Comey as FBI director. Photograph: Saul Loeb/AFP/Getty Images

Mueller, who was named FBI director by George W Bush and held over by Barack Obama, enjoys a reputation for integrity among officials on both sides of the aisle. Trump has said Mueller “is very, very good friends with [James] Comey, which is very bothersome” but also said “Robert Mueller is an honorable man”. Mueller’s critics have accused his operation of having a partisan tilt based on past campaign donations to Clinton and Obama made by at least five legal team members. But others have argued the donations are neither unusual nor evidence of anti-Trump bias.

A pattern of attacks. Trump’s witch-hunt accusation is not his first attack on the rule of law. He branded Comey a liar and said the FBI was a “mess”. He has attacked judges and courts after rulings he did not like on immigration policy or his proposed travel ban. He publicly criticized the attorney general for a decision he did not agree with. As president, Trump has displayed a unique tendency to make baseless attacks on the justice department. But also as president, he has a unique ability to amplify those attacks and to make them devastatingly effective, eroding faith in the process.

A pattern of obstruction? Trump’s tendency to attack the process may ultimately backfire. Legal scholars have warned that Trump’s attacks on the special counsel investigation and justice department could amount to obstruction of justice by the president.

If Trump’s lawyers have warned him to stop tampering with the process, however, he has not heeded that advice. On 27 October, Trump tweeted: “It is now commonly agreed, after many months of COSTLY looking, that there was NO collusion between Russia and Trump.”

That wasn’t true, and it could be seen as an attempt to influence the outcome of the case. Later the same day, reports emerged that the first charges in the case had been filed. And just three weeks earlier, the Republican chairman of the Senate intelligence committee, Richard Burr, said: “The issue of collusion is still open.”