Theresa May’s humiliating rebuff by European Union leaders in Austria this week has many proximate causes and one common root: Brexit threatens the stability and integrity of the EU, while downgrading the UK’s diplomatic and economic standing in the world. No British prime minister taking on such a project can expect help from continental counterparts. Nor can they anticipate gratitude for their actions at home as the painful consequences emerge. Mrs May today tried to regain the initiative with a Downing Street statement. She reaffirmed familiar opinions. She rejected off-the-shelf models of association with the EU, the Norwegian and Canadian templates, on the grounds that the former retains too much Brussels jurisdiction, while the latter requires too tangible a border in Northern Ireland. She restated opposition to a second referendum, and trumpeted Britain’s readiness to embark on Brexit next year without any deal. To underline that point, she offered reassurance to EU citizens resident in the UK that their existing rights will be respected. For that to even need saying is testimony to the way ministers have allowed this process to be shrouded in confusion that in turn stokes alarm. This was panic dressed up as statecraft.

Meanwhile, the broader terms of the UK’s position recall the prime minister’s most notorious accidental catchphrase: “Nothing has changed.” Only now the tone is more defiant and, as a result, the temperature has risen. Mrs May is doubling down on her Chequers blueprint, and calculating that the EU side, perhaps regretting the Salzburg snub, will be more accommodating. That is not impossible. Work in Brussels was already moving slowly but not unproductively towards compromise behind the scenes. But Mrs May’s fundamental problem is located in domestic politics, not in Brussels, and cannot be dismissed with angry glares at the camera. It is this: all models of Brexit sit on a spectrum between wanton national self-harm and damage limitation. There is no painless path that might allow a government to fulfil the referendum mandate without severe cost. The moribund Chequers plan is no exception. Another prime minister might have navigated the brutal dilemmas of Brexit better, but no government could have avoided them altogether. A test for all parties during the present conference season is how honestly that fact can be addressed. For Labour the challenge is to evolve its Brexit position beyond tactical calibrations.

There have been compelling reasons for caution. There is a tension between a broadly pro-European membership and leave voters in constituencies that Labour wants to win. It is also normal for opposition parties to see events through the lens of electoral advantage and to see a general election as the best mechanism for dealing with bad government. Understandably, that remains the preference of the Labour leadership. But Brexit has reached a critical stage that demands a response in terms of immediate national interest, not just party preference. Labour activists recognise that imperative and have rightly been organising to make sure the party has a full and open debate on the subject at its conference – including the question of whether another referendum might be necessary to avert catastrophe.

That is the right conversation for Labour to be having. The chances of that happening at the Conservative conference in Birmingham the following week are slim. Mrs May’s statement confirmed that she has no back-up plans and no reserves of diplomatic capability. It was a performance intended to show strength that only proved her weakness. And that sets the tone for the Tory conference. There will be much Eurosceptic bombast and precious little engagement with substantive, viable routes out the impasse to which Mrs May’s leadership has brought the country. It is dangerous to be so far along the Brexit process without a plan that takes into account fundamental dilemmas arising from the economic and strategic realities of our former relationship with the EU. But no less alarming is the apparent reluctance or inability of a whole generation of political leaders to express those dilemmas honestly to the country.