In a speech on Monday, the Labour leader Jeremy Corbyn will promise he "will do everything necessary to stop a disastrous no-deal Brexit".
Other opposition parties agree with him on stopping a no-deal exit; as many as 40 Conservative MPs support that aim.
But there’s also agreement that Mr Corbyn is not the leader to head up an alternative cross-party 'emergency' government, in the event that Boris Johnson loses a vote of no confidence.
Many Labour MPs do not want to see their own leader installed in Downing Street. An extraordinary position.
The toxic damage done by accusations of anti-Semitism and subsequent infighting has left Labour divided.
A leader who seems unable to unite his own party is therefore not seen by all as the person able to unite a coalition to block no deal.
The Labour leader’s speech on Monday is at a children’s centre in the marginal seat of Corby.
A Labour target and another hint, as if we needed one, that an election may be just a couple of months away.
On that scenario, Mr Corbyn will say: "Labour believes the decision on how to resolve the Brexit crisis must go back to the people.
"And if there is a general election this autumn, Labour would commit to holding a public vote, to give voters the final say, with credible options for both sides, including the option to Remain."
Voters have been confused by Labour’s Brexit policy.
The evidence for that was seen in the European election results.
When Labour campaigners were asked on the doorstep if the party was Leave or Remain the answer was often seen as muddled.
The party’s current position, formed in the aftermath of the European elections, is to back a referendum to stop a ‘Tory Brexit’.
Labour would campaign for Remain or a "credible" alternative option.
What that credible option will look like is not yet decided.
Theresa May’s deal with Labour tweaks?
More on that at the party conference in the autumn.
The precise detail is left in the air.
Speaking to Downing Street advisers there is almost a relish that they may be bounced into an election.
"We’re not planning for an election," they say but it might well suit Mr Johnson, with his working majority of one, to fight an election that can be framed as the prime minister versus the 'Brexit wreckers'.
Lumping Labour, the Lib Dems, SNP and the EU all into a 'coalition of chaos'. That old campaign chestnut.
The problem for the Tories remains their own long-standing splits over Brexit.
The leak of 'Operation Yellowhammer' - Whitehall's no-deal damage assessments - is being blamed on a former minister.
It exposes the fact that not all Tory MPs, some former Cabinet ministers, want to see Mr Johnson take the UK out of the EU without an agreement.
Their votes will be keenly watched in the event of a vote of no confidence.
Will they really enable a Corbyn-run government?
Meanwhile, the EU seems to be biding its time, waiting for the return of Parliament in two weeks, to see if Labour can force an election which would require an extension of Article 50.
That sense of anticipation allows Downing Street to condemn those openly agitating to block no deal as also thwarting any chance of negotiations with the EU.
One option for Mr Johnson is to call an early election himself, to call the bluff of the Labour leader and other parties threatening a vote of no confidence.
Would Mr Corbyn back a vote for an early election in those circumstances?
If it is the case that the country, and the EU, are waiting on Parliament to beat a new path out of the Brexit crisis they may well not be holding their breath.
MPs, and the parties themselves, haven’t had a good track record in providing a clear message to the public.
Mr Corbyn says a general election will be a "crossroads for our country - a once-in-a-generation chance to change direction".
The thing is some parties, like Labour, seem to be advocating a U-turn, others, like some senior Tories, an emergency stop, while voters are left thinking we’re all on the motorway heading to an election which may not lead to a final Brexit destination.