In electing to whip his MPs to support Lords reform, Ed Miliband has taken a bigger political gamble than most appreciate. Labour is not as divided as it was over the Alternative Vote but, for both political and principled reasons, a significant chunk of the party is implacably opposed to reform. I'm told by a Labour source that the "net majority" of those who spoke at yesterday's PLP meeting believed the party should vote against the bill at second reading.
In addition, those in Labour who opposed AV are worried that Lords reform could become "a backdoor way of getting PR in" (a fear shared by Tory MPs). As I've noted before, one reason why the Lib Dems are so keen to secure an elected chamber is that it could revive the debate around electoral reform. The use of the proportional Single Transferable Vote (the Lib Dems' voting system of choice) to elect the second chamber would allow Nick Clegg to portray the Commons as a less legitimate body and argue for reform to bring it into line with the Lords. Indeed, Lib Dem president Tim Farron has already argued that "Members elected in a different Chamber by the single transferable vote will have greater legitimacy than those elected to the Commons on a system of first-past-the-post" (see p. 14 of the joint committee report on Lords reform).
Finally, while Labour continues to support a fully-elected house, as opposed to one that is part-appointed (in this case, 20 per cent of members), I'm told that the party will not let "the best be the enemy of the good". The issue is not a "deal-breaker".