And they’re off.

Boris Johnson popped up on TV yesterday having neatly trimmed his trademark blond mop, sparking renewed speculation of a leadership bid.

On another channel, Esther McVey said she would run to be Tory leader if asked to by colleagues.

The sharks are circling around Theresa May ahead of this momentous week in British politics.

Amid such extraordinary political crisis, you would imagine that nobody who aspired to be Prime Minister would desire the job at this moment in time.

Conventional wisdom dictates that the government of the day should be languishing in the polls, ready to be put out to pasture by the great British public.

But, extraordinarily, the Prime Minister enters this dramatic week with her party neck-and-neck with Labour in the polls – or even with a slight lead, according to some pollsters.

She has presided over a ‘failure of British statecraft on a scale unseen since the Suez crisis’, according to Jo Johnson. But voters would still consider re-electing her government in a general election.

What a damning verdict on Jeremy Corbyn. Even as we teeter on the brink of a national emergency, millions of voters are still saying "yes, but Corbyn would be worse".

Just imagine the damage that Tony Blair or Gordon Brown would have inflicted on the government in the Commons in recent weeks. Or imagine the damage Yvette Cooper would be doing right now if she was Labour leader.

Instead, she is left to speak from the backbenches from time to time, besting May on every occasion and reminding her how fortunate she is that it’s Corbyn sitting directly opposite her.

In Parliament today, it is backbenchers from all parties who are making the most impact, while the opposition leaders flounder.

Corbyn is a lifelong eurosceptic who is perfectly happy to go along with Brexit. That we were saved from a TV debate last night between two politicians who fundamentally agree we should leave the EU is a festive blessing.

On Friday, Corbyn jetted off to Portugal to address left-wing politicians from across Europe. Those in the audience, who perhaps haven’t followed the Brexit debate as closely as we have in Blighty, were expecting to hear opposition to the constitutional chaos.

Instead, they were lectured about "failed neoliberal policies" and informed that Labour would negotiate a better Brexit deal.

"Fanciful", one attendee said afterwards, with many delegates simply left horrified by Corbyn’s claims.

You can’t pin a red rosette on a unicorn and expect people to believe it exists.

Not that his fellow opposition leaders in the Commons have performed much better.

Vince Cable continues to make a meal of being interim LibDem leader, while those who favour the best parliamentarians being in charge wait impatiently for Jo Swinson’s reign.

Ahead of this week’s crunch votes, the LibDems have managed the impressive feat of infuriating their allies in the People’s Vote campaign.

The party has tabled an amendment to May’s Brexit deal calling for "all necessary steps" to prepare for another referendum on EU membership. But the People’s Vote campaign, which has performed tactical masterstrokes throughout the year, is adamant that the timing is wrong for this. Strategists want the deal to be defeated before more work is put in to build a parliamentary majority for a People’s Vote – rather than holding a vote in the Commons when there still aren’t enough MPs on board for it to pass.

Cable ignored the advice and is now ostracised from the campaign.

For the SNP, Westminster leader Ian Blackford – unlike Corbyn – chooses the right topic at PMQs. But few are listening. He has failed to earn the respect that his predecessor Angus Robertson had, and by the time he is on his feet, MPs’ minds have drifted to the jerk chicken in the Commons canteen.

May no longer feels the need to prepare for SNP questions in the way that she and David Cameron did when up against Angus Robertson.

But while the Westminster leaders are letting the PM off the hook, the talent on the backbenches is making her premiership a misery.

There are some who believe Hilary Benn’s amendment to the meaningful vote – which rejects both May’s deal and no deal – could allow the PM to live to fight another day because the margin of victory will be narrow, but he has still marshalled moderate forces across the Chamber and secured a likely parliamentary majority against a hard Brexit.

Another Labour backbencher, Alison McGovern, has tirelessly campaigned for over a year for single market membership, relentlessly touring the TV studios, paving the way for the shift towards a people’s vote. For a party with just one MP, Green politician Caroline Lucas has also impressively made her voice heard above the cacophony.

On the SNP benches, Stephen Gethins takes a measured approach to opposing Brexit that doesn’t automatically alienate No voters in the way that his colleagues often do, while Joanna Cherry is part of the "Scottish Six" parliamentarians who launched a lengthy legal fight to determine if Article 50 can be unilaterally halted. The final verdict from the European Court of Justice will be published today.

On the Tory backbenches, Anna Soubry is arguably the most effective of the 15 Conservatives branded ‘mutineers’ by The Daily Telegraph, although veteran Ken Clarke remains a thorn in the PM’s side.

From the other wing of the Tory party, regardless of your views on his politics, Jacob Rees-Mogg has persistently caused more trouble for May from the backbenches than many of the former Cabinet ministers who resigned.

But the most effective backbencher has been Chuka Umunna, the Labour MP who brought together the various pro-EU campaign groups under one roof and transformed them into the People’s Vote organisation.

He has spent months steadily building up support, changing the minds of politicians who this time last year wouldn’t countenance a second referendum.

It has reached the point where Scottish Secretary David Mundell yesterday admitted Parliament "might put another referendum in place, and that ultimately could lead to a reversal of the result".

At the end of this historic week in Parliament, May could still be standing. But the fact that a hard Brexit is no longer inevitable is a testimony to the backbench MPs who sit on those famous green benches which surround her.