Lords inflict defeat: is this a taste of what's to come?

Bruising defeats on the Welfare Bill last night - is this just a taste of what's in store for the government?

Peers clobbered the bill - striking down planned restrictions on employment and support allowance (ESA) affecting cancer patients and the disabled, and a proposed one-year limit on ESA claims (worth £1.6bn) - and they could well do more damage as report stage continues.

A combination of Labour peers, Crossbenchers and Lib Dem abstentions did the damage - and left the Work and Pensions ministerial team promising to reverse the defeats at a later stage…. but can they? Given the comfortable majorities against the government in last night's vote, they may struggle to do so in the House of Lords, unless they can offer some kind of compromise to buy off some of their opponents.

So they will have to get the Commons to reject the Lords amendments - and then we're in to the end of term nightmare for the whips and the footsloggers alike, known as "Parliamentary ping-pong."

Both Houses of Parliament have to approve a bill in its final form, before it can become law. And where they disagree, the bill bounces between them, until negotiation or sheer fatigue results in some kind of solution. And the process for the Welfare Reform Bill (and several others, I expect) will be conducted against a deadline. The bills have to be passed before the end of the parliamentary year - or they are lost. (There is a carry-over procedure, but it would not normally be invoked for bills at this stage of consideration, in these circumstances).

So this is one of the rare moments when the Opposition in Parliament can exercise real power - if they can continue to turn out their troops. Expect a long series of late night sittings in March and possibly April, as the deadline looms ever closer.

If they do, ministers may be forced to compromise - or seek another route to get their changes through. One thought is that the bill or some clauses of it could be deemed to be a money issue - which under the Parliament Act could not be amended by the Upper House. That's the result of the titanic constitutional battles fought a century ago, when HH Asquith's Liberal government faced down the House of Lords.

It does seem a little retrospective to invoke that provision after the bill has been in committee and through all kinds of votes already. This kind of thing doesn't happen very often, but my guess is that a ruling by Mr Speaker might be required, or possibly just a vote to assert the procedural point. It would be a bruising precedent to set, because MPs would be widening their ability to stop the Lords amending bills…and peers might seek to revenge themselves elsewhere.

Failing that the government would have to try again with another bill in the next session - but that would delay the savings it is seeking to make for many months. And remember, the same thing could happen on attempted savings on legal aid and other provisions in other bills.

This could get nasty.