This week MPs will again debate the withdrawal bill to take the UK out of the EU. Soft Brexiters are increasingly confident, while the most prominent Leaver is plunged in gloom

When Nigel Farage emerged from a meeting in Brussels with the EU’s chief Brexit negotiator Michel Barnier shortly after midday last Monday his increasingly gloomy mood had darkened further. “The message I got was that they will be happy to trade chocolate and cheese and wine freely with us but when it comes to services, forget it. It ain’t going to happen. I think we are going to have a very bad deal.”

In the early hours of 24 June, 2016, the former Ukip leader, who had, arguably, done more than anyone to deliver the Leave vote, toured TV stations, triumphantly hailing the UK’s “independence day”. In Farage’s view it was not only a defining moment for Britain. It was also one that would demonstrate to other EU member states with strong or emerging eurosceptic movements – he cited Denmark, Italy, Sweden and Austria – that there was another way. “The EU is failing, the EU is dying. I hope that we have knocked the first brick out of the wall,” he declared in the glow of victory.

Nineteen months on, that joy and optimism have been replaced by doubt and fear. These days Farage is a genuinely worried man. He deeply regrets that the Leave campaign effectively “shut up shop” the day after the referendum, believing it was job done. The result of doing so, he told the Observer on Friday, was that the Leave side is now being seriously outgunned by well-funded, well-organised supporters of Remain who are intent on overturning the referendum result.

Three days after his meeting with Barnier, Farage went on TV again and said he was coming round to the view that a second referendum might be the only way to regain the initiative, to cement Brexit and shut down the issue for a generation. He said then that he thought Leave would win again, and by a bigger margin.

But on Friday he was less sure – and revealed the real depth and root of his anxieties. The momentum, he made clear, was running away from the Leavers. They had vacated the field for Remain to run all over. Anti-EU MPs were making a grave mistake, he argued, if they believed that parliament and the British people would just accept any deal that Theresa May could extract. Leavers needed to mobilise for the cause.

“There is no Leave campaign,” Farage said. “I think Leave is in danger of not even making the argument.” He added: “I feel like I did 20 years ago when it looked like we were heading into the euro. We had to set up Business for Sterling to stop it.” Things felt eerily familiar now. “The Remain side is making all the running. They have a majority in parliament and unless we get ourselves organised we could lose the historic victory that was Brexit.”

With the clock ticking, and with parliament having voted to trigger the article 50 process that puts the UK on the legal track to leave the EU on 29 March next year, it is still extremely difficult to see how the Brexit train can be derailed entirely.

But Farage’s interventions over recent days are highly significant, and about far more than the rogueish populist yearning to be back in the headlines. He is nothing if not a shrewd interpreter of prevailing political and public moods. “He is dangerous – and brilliant, in equal measure,” says one ardent Tory MP from the Remain side. “We know that from painful experience.”

Farage fears a very soft Brexit as much as no Brexit at all. And he is not alone in spotting that the forces favouring soft Brexit – in Westminster at least – are now in the ascendancy. It is not just pro-Remain Labour MPs who are marshalling their troops to great effect to demand that their party and parliament as a whole backs as close a relationship as possible with the EU after March next year.

Where John Major and David Cameron had rightwing Eurosceptic rebels to deal with, May, with no Commons majority, now finds her biggest problems coming from those on the pro-EU left flank of the Tory party. Her chaotic reshuffle last week added new recruits to that ever more confident rebel army, among them sacked education secretary and Remainer Justine Greening.

At prime minister’s questions last Wednesday, the day after she left the cabinet, Greening arrived early. When anti-Brexit Tory rebel Dominic Grieve came into the chamber, Greening caught his eye and patted on the vacant seat by her side in a gesture that invited him to be her new neighbour in the naughty soft Brexit corner. Grieve duly accepted.

“It was a fantastic moment for us,” said another in the group, who added that May had made a big mistake ousting the MP for Putney from the cabinet. “A Remainer, from Rotherham, educated at a state school. Who just happens to be in a same sex relationship. How many bloody boxes does she tick for us? For too long this party has been run by a few rightwingers intent on destroying our country. Now we are taking the party back.”

Ryan Shorthouse, director of the modernising Tory pressure group, Bright Blue, said: “Before Theresa May became prime minister, for decades Conservative governments only really faced concerted pressure on the backbenchers from the right of the party. Now, there is a group of high-profile and senior backbenchers on the ‘one nation’ wing who are increasingly co-ordinated, empowered and outspoken.”

This week will be another crucial one in the parliamentary battle on Brexit, over which Farage is agonising. The EU withdrawal bill will complete its third reading and report stage in the Commons on Wednesday before heading to the House of Lords, where it faces a mauling, not least from dozens of pro-Remain peers who favour a second referendum.

Before Christmas, Grieve, a former attorney general, led a successful Tory rebellion against hard Brexit to ensure MPs will have to vote for a new statute before any Brexit deal can be agreed. The effect is to give MPs a vote – and an effective veto, on the outcome of negotiations with Brussels – something the hard Brexiters were determined to resist.

This week the focus will be on Labour, as a growing number of Jeremy Corbyn’s MPs put pressure on their leader to adopt a firmer pro-EU, pro-single market line. Upwards of 60 Labour MPs are now believed to back permanent membership of the single market and customs union after Brexit and are ready to rebel.

Labour has already come a long way down the soft Brexit road – but not far enough for dozens of its MPs. Last summer, shadow Brexit secretary Keir Starmer shifted to support membership of the single market and customs union during a post-Brexit transition of up to four years.

He is now being urged to go much further. This weekend, in a sign of that pressure, the leadership announced it would back an amendment tabled by former shadow Scottish secretary Ian Murray, which he drew up in the belief it would leave the party effectively backing single-market membership for the long term.

The amendment says that, after the final Brexit deal is done and known, Labour will insist on a full independent economic analysis, involving the National Audit Office, the Office of Budget Responsibility, the government actuary’s department, and the finance directorates of each of the devolved administrations, before MPs vote on the final deal.

Chuka Umunna, one of the Labour MPs leading cross-party efforts to secure a soft Brexit, sees this as a step forward, though still an insufficient one.

“This is a significant move, which shows we are rightly focusing on the need to demonstrate what the economic impact of Theresa May’s Tory Brexit will be on people’s lives.

“If such an assessment is not carried out, or if it is and concludes that a Tory Brexit deal would be bad for the economy, we should oppose it. Labour should be clear that at a minimum we should back single market and customs union membership (or full participation) for good.” Meanwhile peers – including many who take the Tory whip – are joining cross-party alliances in an attempt to secure long-term single-market and customs membership.

Some are also planning amendments calling for a second referendum before the UK leaves the EU – the same suggestion as that made by Farage on Tuesday.

On Saturday it emerged that, following Farage’s meeting with Barnier in Brussels last week, it will be the turn of Tory Remainers Grieve and Anna Soubry and Labour MPs Leslie, Umunna and Stephen Doughty to bend the ear of the man leading the EU negotiations on Brexit.

Their meeting with Barnier will be another blow to Farage – and further confirmation of his growing conviction that victory for Leave on the night of 23 June 2016 was far from the end of the story.