What had looked for Malcolm Turnbull like a tough but doable task of getting his partyroom on side for a CPRS deal with the Government has become a nightmare with former Turnbull supporter Andrew Robb declaring he’s opposed to the deal.

Robb was Turnbull’s original choice to lead the CPRS process, but had to bow out when he was felled by an illness earlier in the year.  He was replaced by Ian Macfarlane, who has negotiated the package released today with Penny Wong.

Robb’s opposition to the deal will lend respectability to those opposing a deal, who are primarily climate denialists.  While initially a climate sceptic, Robb immersed himself in the detail of emissions trading and visited the US for discussions with carbon markets analysts there.  After Turnbull, Macfarlane and Greg Hunt, Robb is the Liberal figure who understands the detail of the CPRS and emissions trading best.

He is also the most substantial senior Liberal after Turnbull himself, respected in Parliament and in the Press Gallery.

Robb will be fully aware of what his opposition will do to both the chances of a deal and to Turnbull’s leadership.  It is, quite literally, a gamechanger, and leaves Turnbull in serious trouble.  This could be the end of Turnbull’s leadership.

The partyroom meeting resumes at 4.00pm after a break for Question Time.