'Constitutional chaos' - that's the PM's verdict if Lords go ahead and vote against the government's changes to tax credits today.
There are hints from the PM that he is threatening to stuff the House of Lords with 100 extra Conservative Peers if the upper chamber goes against Ministers' wishes and opposes the cuts.
Yet at the ERS we've worked out that 100 extra Peers would cost at least £2.6million per year - around £26,000 is claimed by the average member of the upper chamber every Parliamentary session.
If it really will be 'constitutional chaos' for the revising chamber to reverse this decision, we've got a pretty handy solution. How about the Prime Minister backs an elected upper chamber?
If the government is serious about tackling any potential constitutional crisis, instead of adding up to 100 extra Tory Peers they would do well to introduce a fairly-elected upper house - with a clear remit as to what its responsibilities are.
Instead, at the moment we have the bizarre situation of the government claiming that an unelected upper chamber is a wonderful revising body...but then threatening to pack it with cronies if it doesn't vote the way Ministers want it to. What's the point of the Lords if they're overruled almost every time they suggest a change?
A chamber built on vague conventions and illegitimacy is no way to deal with legislation, and is simply asking for constitutional chaos and confusion.
It's not just a cost issue, although £2.6million is a lot of money. An additional 100 Peers would take the Lords to nearly a thousand members - far more than our elected Commons. So the government is cutting the number of MPs from 650 to 600 on the basis of austerity, while packing the upper chamber with pliant Peers. Something is constitutionally askew here.
The actual cost is likely to be much higher than £2.6million, since that figure doesn't take into account the increased staffing, office and infrastructure costs 100 extra Peers would entail.
Between February 2014 to January 2015, £21million was spent on handouts to members of the House of Lords, with the average Peer receiving £25,826 tax-free - despite the chamber only sitting for about 130 days of the year.
Adding an extra 100 Tory Lords at a time of austerity would not only be unpalatable but would be frankly scandalous - and a constitutional crisis in its own right.
We think it's time for real reform - not the undemocratic and partisan packing of our legislature.
Agree? Spread the word and let the government know there's a better way of dealing with democratic issues than appointing dozens of cronies.
For more of the ERS' research on the House of Lords, see our recent report, "The House of Lords: Fact vs Fiction".