FBI director James Comey told the House Intelligence Committee this week not just that his agency is indeed investigating possible collusion between Donald Trump's 2016 campaign and Russia and its meddling in the presidential race but also that it began the effort as long ago as July last year.

My guess is that 27 July is the day it started, a Wednesday. The Democrats were midway through a national convention in Philadelphia that had opened under the cloud of a huge leak of hacked Democratic National Committee memos suggesting that its officials had deliberately plotted to ease Hillary Clinton’s path to its party’s nomination at the expense of Bernie Sanders.

The day before, meanwhile, Donald Trump, already crowned at the Republican convention a week earlier, had boldly stood before reporters and, in terms, invited Russia to quarry for emails he said Clinton still hadn’t surrendered from her private email server. Jaws slackened across the land. The following day – as the FBI was presumably swinging into action – there was a 76 per cent spike in ordinary Americans looking online for definitions of the word “treason”.

“Russia, if you’re listening, I hope you’re able to find the 30,0000 emails that are missing,” Trump said. At the time, I wrote that should we discover that his campaign had egged Russia on in any way, the resulting scandal would make Watergate look like small-fry. I also said Trump was building a manure hill that would bury him well before the November vote.

So much for that. Like others, I was underestimating Trump’s teflon armour. As we were to find out later, even fall-out from recordings of his boasting about grabbing the body-parts of women wouldn’t be enough to penetrate it.

But if my timing was off, my death-by-manure prognostication may yet come to apply – the day of reckoning may only have been delayed. Now when he is meant to be in the salad days of his presidency – with public support strong (it’s not) and gratitude from his own party bottomless (questionable also) – he finds himself under the cloud of an investigation that could dog him for months or even longer and maybe, just maybe, end up removing him from power entirely.

If not Trump himself, who are the targets of the now eight-month-old probe? Names mentioned in the course of the House hearing, though not by Comey, included Paul Manafort, who last July was still Trump’s campaign chief having previously steered the successful election campaign of pro-Moscow Ukrainian president Viktor Yanukovych (subsquently overthrown), Roger Stone, a long-time adviser who seemed last year to have inside knowledge of when damaging leaks of Democratic communications were coming, and Carter Page, another Trump campaign adviser.

Everyone may yet be exonerated. But the mere fact of the investigation happening is terrible news for Trump and his team, who should be focusing all their energies on the repeal and replacement of Obamacare and the implementation of all the rest of the Trump agenda from immigration to fighting Isis, remaking the federal budget and tax law and reworking trade policy.

“There’s a big grey cloud that you’ve now put over people who have very important work to do to lead this country,” the House Intelligence Committee chair Devin Nunes, a California Republican, informed Comey at Monday’s hearing, as if he wasn’t already aware of it. “The faster that you can get to the bottom of this, it’s going to be better for all Americans.”

Speed was not something the Republicans looked for when they blew on the embers of scandal surrounding former President Bill Clinton in the 1990s, leading quickly to the appointment of Kenneth Starr as special prosecutor. Starr spent five years – yes, five dreary years – looking into everything from the President’s land speculation deals in Arkansas to the death of Deputy Counsel Vince Foster and, finally, his liaison with White House intern Monica Lewinsky.

There is ample reason why a special prosecutor would be appropriate again now. Confidence in the FBI being able to insulate itself from political pressure is low. Note the barrage of tweets coming from Trump and the White House even as Comey was testifying on Monday. It hardly helps that the US Attorney General, Jeff Sessions, was forced to recuse himself from the matter entirely soon after being sworn in after it emerged that he had himself met with top Russians while advising the Trump campaign last year and then testified to the contrary under oath.

And there is the sheer gravity of what has been alleged. Congress began impeachment proceedings against Bill Clinton because he had lied under oath about an affair. Richard Nixon was forced from office because his party broke into the offices of the opposing party for electoral advantage and he then sought to cover it up. Bad hombres, both, you might argue. But these were sins of the home and the homeland, domestic in nature in the broad sense of the word.

Comey summed up why what we are discussing here is of a different order. “One of the things we radiate to the world is the importance of our wonderful, often messy, but free and fair democratic system and the elections that undergird it,” he said. “When there’s an effort by a foreign nation state to mess with that, to destroy that, to corrupt that, it is very, very serious. It threatens what is America. And if any Americans are part of that effort, its a very serious matter.”

It reminded me of what Trump says about strong borders: without them, America doesn’t exist. Comey is saying that America would also cease to exist the day a candidate recruits a foreign power to subvert its democratic process. America last, not first. And remember, we are talking Putin’s Russia here.