The government's modest band of supporters in the Lords are mounting a formidable filibuster operation to prevent the Benn Bill - the bill which aims to prevent no deal - getting to third reading before a possible prorogation of Parliament on Monday.
Labour and the Lib Dems had put down a business of the house motion which lays down a timetable for consideration of the bill.
And the government side has unleashed hordes of amendments, to change every possible aspect of the motion and suggest all kinds of measures that should be debated instead (my favourite is the Bat Habitat (regulation) Bill).
Unlike the Commons, where such amendments might be grouped or voted on in a job lot at a set time, the Lords has to debate each amendment.
So the bill's supporters will have to move a closure motion to end the debate on each amendment, and then vote on each amendment.
That will mean two divisions, each probably taking a quarter of an hour, will be forced on each of around 90 amendments.
And the pro-bill peers, Labour, the Lib Dems and many Conservatives plan to simply keep sitting and voting until the job is done.
Rotas are being organised to ensure they have enough peers on hand to keep voting down the much smaller band of pro-government Lords - and if the latter don't crack from sheer exhaustion the Business motion should be passed come Saturday lunchtime.
At that point the business motion allows them to impose a brisk timetable to get the bill through on Sunday, in good time to receive Royal Assent before the Prime Minister can prorogue.
"Time is their weapon, numbers are ours," one senior pro-bill peer told me.
He expected a combination of exhaustion and, er, peer pressure, especially from exasperated crossbenchers, to bring the filibuster to a close.
Are peers heading to infinity, and beyond?
So if Hilary Benn's anti no-deal measure clears the Commons tonight, the effort to get it through the House of Lords could see peers sitting into Sunday.
This morning, many were arriving with suitcases full of overnight gear and supplies.