It’s rare that one side tells the truth about the other in Question Time, but Lindsay Tanner had it right yesterday when he referred to the Liberals as being held hostage by Nick Minchin and the climate denialists in Liberal ranks.

The show of Senate strength yesterday by Minchin’s supporters in his war on the CPRS and — by proxy — on Malcolm Turnbull sent a clear message to the rest of the party: even if we’re not the majority, you can’t ignore us.

Too small to win the debate, maybe, but too big to hope they will accept defeat gracefully. They can legitimately mount a claim that they need to be accommodated for the sake of party unity.

And Tony Abbott, insisting that the Government must accept every single amendment or there’ll be no deal, has sent a clear signal to party conservatives that he’s no longer in the Turnbull camp on the issue. Earlier this year, Abbott was arguing that regardless of whether they believed in climate change or not — and he doesn’t — the electorate wanted action and the issue was hurting the Coalition.

So now the party conservatives and denialists have a leadership candidate in Abbott, as opposed to Joe Hockey, who is strongly backing the Turnbull line on the ETS. The problem for the conservatives thus far has been that rolling Turnbull and forcing him out wouldn’t produce a leader with a different approach on climate change, given both Hockey, the likely successor, and Abbott wanted the issue dealt with and removed from the agenda.

Now Abbott has signalled he’s their man.

That goes some way to neutralising the problem that a partyroom vote on accepting a deal with the Government would be a de facto vote on Turnbull’s leadership.

Turnbull’s only real option in the face of this entrenched opposition is to tell his shadow Cabinet and the partyroom the deal Ian Macfarlane has extracted from Penny Wong, no matter how good it is, isn’t good enough. That would hand victory to Minchin and his allies, but anything else risks a deep split within the Liberals or, worse, a defeat for Turnbull that will in effect force him out. And there’ll be very few of his colleagues, even among his former supporters, who will beg him to remain.

Minchin might win the battle but he’s orchestrating the mother of all defeats in the war. The climate denialists in the Coalition might delude themselves that voters are “waking up” to green alarmism and the costs of an ETS. (Let’s see what a long summer of bushfires and heatwaves does to that conviction.)

Any climate scientist worth a damn will say — contra Kevin Rudd’s antics in Question Time yesterday — that you can’t be sure higher temperatures have any relation to climate change, but voters persistently say they want action on climate change and that isn’t going to change as they sweat their way through Christmas and the New Year.

In truth, the Liberal Party is caught in a terrible bind because neither side in the debate has the numbers to win a complete victory. The party was unified for so long under John Howard because, especially after the systematic execution of moderates in the late 80s, the party’s progressives always lacked the numbers and had to choose the issues on which they rebelled carefully. Now the party is led by two moderates in Turnbull and Hockey, but they lack anything faintly resembling the dominance Howard had, leaving conservatives like Minchin and Abetz to plot in senatorial safety.

If it was the ALP, the issue would have been resolved — clumsily, with protests and anger and perhaps some bloodshed, but resolved — by the factions. They did it with asylum seekers after 2001. They’ve done it with uranium mining.

In contrast the Liberals, bereft of formal structure and dependent on the authority of the leadership, look condemned to eternal war on climate change, until one side or the other manages to purge the party’s ranks of most of their opponents.

The Liberals need a deal next week with the Government to get climate change off the agenda. If not, it’s going to wreak havoc in their party far beyond next Tuesday and even the next election.