Zac Goldsmith is 'very tempted' to support Labour at next election
Zac Goldsmith - who quit the government over its alleged climate change "apathy" - has said he is "very tempted" to back Labour.
The Conservative peer criticised his own party for not having "a clear answer" to what he called the "biggest challenge we've ever faced".
He told the BBC's HARDtalk he was "desperately hoping the Conservative Party comes to its senses."
But he was seriously looking at switching his support to Labour.
"The simple truth is there is no pathway to net zero and there's no solution to climate change that does not involve nature, massive efforts to protect and restore the natural world.
"And at the moment, I'm not hearing any of that from the Labour Party if I do, if there's a real commitment now the kind of commitment, frankly, that we saw when Boris Johnson was the leader, then I'd be very tempted to throw my weight behind that party and support them in any way I could."
Lord Goldsmith is a close ally of former prime minister Boris Johnson and was the government's international environment minister until he quit in June, after being among those accused of interfering in an MPs' inquiry into partygate.
In a scathing resignation letter, he said he had been "horrified" at the government abandoning its environmental commitments and withdrawing its leadership on the world stage.
As international environment minister, the former MP and London mayoral candidate travelled the world championing the UK's environmental initiatives, as well as promoting legislation to ban trophy hunting.
In his HARDtalk interview, Goldsmith also said the government can't meet its target to spend 11.6bn over five years in international climate change programmes.
"It's great that the government is saying that they're committed to 11.6, but mathematically, it is impossible for us to meet that target.
"Unless the Treasury intervenes, unless the prime minister intervenes, it's simply impossible.
"If you look at the trajectory of expenditure, in order to fulfil that promise the first year of the next government, which may or may not be this government, it might be the Labour Party, will have to spend over 80% of all of its bilateral aid on climate finance and that it obviously is not going to happen."
Rishi Sunak has insisted he cares about reaching net zero but that the 2050 target needs to be achieved in "a proportionate and pragmatic way".
The prime minister told LBC last week he wanted to leave the environment in "a better state than we found it in" for his two daughters.
Mr Sunak is facing pressure from some Conservative MPs to review the government's green policies, after the party's surprise win in the Uxbridge by-election, when it capitalised on anger over London's Ultra Low Emissions Zone (Ulez).
You can watch the full HARDtalk interview with Lord Goldsmith on BBC News on Thursday and on the BBC World Service Radio on Friday - or on the BBC iPlayer.