Even for an issue that has been characterised by spin, stunts and the government’s grating and relentless political opportunism, Penny Wong’s letter to Malcolm Turnbull on the CPRS timetable is a particularly low-rent effort to further damage the Liberals.

Remember that the government’s priorities on climate change are to first to inflict as much damage on the Opposition as possible, and secondly to get its CPRS legislation passed, and thirdly to address Australia’s contribution to climate change. They’d be happy to get all three, of course, but 1. would be nice and 1. and 2. real beaut.

That’s why the government, via the ever-more sanctimonious Wong, has shifted its CPRS game from the Senate to the Coalition party room, where Turnbull faces a severe leadership test to get a decent majority of his Liberal colleagues to back a deal with the government.

Wong’s letter demands that the Opposition front up with its amendments on the first day back from (yet another) parliamentary break. That’s October 19. Yesterday, Ian Macfarlane, the climate sceptic and member of Clive Hamilton’s “dirty dozen” greenhouse mafiosi who finds himself filling in for Andrew Robb on the ETS, indicated he would have a set of amendments ready for consideration by his colleagues in the party room meeting of that date. The Opposition leadership is planning to use the sittings to get recalcitrants in their own ranks on board. Wong, in a bizarre intervention in another party’s internal processes, is demanding that the Coalition settle its position once and for all in that October 19 meeting.

Remember, this is for a scheme that won’t now start for just under two years.

The purpose of Wong’s letter is two-fold. It is intended to focus more attention on the Coalition’s problems, and those of the Liberals in particular, in working out a position. And it is intended to reduce the chances of the Liberal leadership doing just that.

Turnbull has had to play a patient game with his colleagues, coaxing them bit by bit to the realisation that the government has them over a barrel on climate change and it is in the Coalition’s best interests to get the issue off the agenda and avoid the possibility of a double dissolution election. It has taken time to get them this far and will take longer to get them to support a scheme of any kind. For all the claims — justified — of Turnbull’s bull-at-a-gate approach, he has been subtle and effective at poking and prodding his party in the right direction.

If Turnbull fails — particularly if his party room rejects his amendments, undermining his authority and scuppering the chances of a deal — it may well be fatal to his leadership. At the very least, it will correctly give the impression Turnbull lacks the authority to lead his party on what is regarded as a key issue by voters.

The government knows this. It’s why the government wants Turnbull to fail in his party room, and that’s why it is pressuring him. It is raw power politics, for very high stakes.

Turnbull’s cause isn’t helped by the emerging split between senators and MPs in his own ranks. Senators at the top of their parties’ Senate tickets can affect insouciance at the prospect of a double dissolution election. They’ll be returned to the red benches without having to lift a finger. Marginal-seat MPs, facing polls showing Labor lifting its vote from 2007, and in some states having had their margins redistributed away from them, may not be so disposed to laugh in the face of death. There won’t be enough Senate recalcitrants to derail the CPRS bill — Turnbull’s shadow Cabinet Senators are enough to ensure passage if they vote with the ALP, even if all backbenchers vote against — but there’ll be plenty enough to badly wound Turnbull in the party room.

What’s amusing about the press coverage of the letter is that, for once, The Oz gave the government the benefit of the doubt, while Fairfax nailed it straight off. “The Rudd government has opened the way for real negotiation and amendments on its historic carbon emissions trading scheme,” said Dennis Shanahan. The tone of Shanahan’s coverage seems to change in a markedly pro-Rudd direction whenever he travels with the PM. Phil Coorey and Anne Davies had it right in the SMH, calling it an “ultimatum” intended to lift pressure on Turnbull, as did David Crowe and John Breusch in the Fin.

And it’s all the more ironic given this is happening while Rudd and Wong are posing in New York as good-faith participants in efforts to achieve a global climate change deal. There’s about as much good faith in the government’s CPRS tactics as there’ll be carbon reduction in the scheme itself.