IT is going to be a fraught summer for Coalition lovers.

David Cameron last night told his Tory MPs there would be "one more heave" to open the door to Lords reform. But, he warned, if the 91 rebels could not be persuaded to hand over the key, then the Lib-Con partnership would have to admit defeat and move on. Which might be easier said than done.

Given Labour has apparently set its face against any motion limiting debate on Lords reform, it seems the only option for the Prime Minister is to persuade many of his rebels to abandon their cause.

And given the Coalition's working majority is 83, this will mean Mr Cameron will need to persuade more than half of the dissenters to give in.

As the Tories talked to themselves yesterday, the LibDems were telling the media in no uncertain terms that if the Conservative leader could not deliver his rebels, then there would be "a chain reaction" (David Laws) and "consequences" (Simon Hughes); "a deal is a deal" (Nick Clegg).

The junior member is linking the fate of Lords reform to the constituency boundary review, which, experts tell us, will deliver the Tories another 20 seats at the next election; the possible difference between victory and defeat for Mr Cameron.

The pressure's on. If the PM cannot charm the rebels by September, the cracks in the Coalition will grow ever deeper.

The death of Lords reform will make Mr Clegg's speech to the LibDems' annual conference rather interesting.