Gordon Brown, Ken Livingstone and 300 Labour councillors were not the only casualties of the local and London elections. No one seems to have noticed, but the other big losers were those people who care about the environment.

We might just look back on May Day 2008 as the moment when the power of green politics peaked and went into reverse. I hope I'm wrong, but I doubt it. The reaction of the two main parties to the elections was instructive. Desperate to prop up his own position after Labour's rout, Mr Brown needed to toss a few bones to the voters and jittery Labour backbenchers. So it suddenly emerged that he was about to dump the so-called "bin tax" – allowing councils to charge householders who do not recycle their rubbish. Downing Street didn't confirm it, and five token pilot schemes will go ahead, but it's clear the bin tax has been binned.

Brown allies also floated the idea that the 2p rise in fuel duty might be shelved again. No doubt this was an attempt to placate motorists. As well as being anti-green, it was a surprise, since the Chancellor, Alistair Darling, will need all the revenue he can get when he delivers his pre-Budget report in the autumn – not least to compensate the losers from the abolition of the 10p tax rate.

Mr Brown was not alone in relegating the environment to the back burner. David Cameron, the wind in his sails after the elections, held a prime ministerial press conference in which he set out his priorities for government. Significantly, the words "environment" and "climate change" did not appear in his 1,200-word statement.

Was this the same man who fought the local elections on the campaign slogan "vote blue, go green"? And was the leader who hugged huskies to convince us his party had changed addressing new issues and no longer preaching to the Tory converted? Green issues have gone out of fashion for Mr Cameron; they have served their purpose.

Naturally, the Tory leader denied it. "We have made quite good progress," he insisted. "I'm not saying the job is done. There is still a huge amount that we want to see changed."

But whatever happened to the impressive tome of green policies produced last year by the Tory policy review headed by John Gummer and Zac Goldsmith, who seems to have disappeared off the planet he was trying to save? When asked, Mr Cameron banged on about the fuel price pressures facing motorists and hauliers.

Officially, the Tories remain committed to raising green taxes in order to cut taxes for families. But they don't talk about it much. After a brief detour, they seem to have arrived at the same point as Mr Brown: that the public needs "carrots" as well as "sticks" to go green; that they suspect green taxes are stealth taxes.

Another reason why the elections have set back the environmental cause is the election of Boris Johnson as Mayor of London. He will dump Mr Livingstone's plan to charge drivers of gas-guzzlers £25 to enter the capital's congestion charge zone, and review its recent expansion into west London. In Manchester, the councillor behind plans for a £5 congestion charge lost his seat to a community party which opposed it.

Labour and the Tories will doubtless argue that the Manchester experience shows they are right to be cautious on green issues. Similarly, Labour MPs say the bin tax was an issue on the doorsteps in the local elections. As The Independent reported eight days ago, a new opinion poll found that more than seven out of 10 people are not prepared to pay higher taxes to fund projects to tackle climate change.

It's hardly surprising that people downgrade soft issues such as the environment when economic times are hard. Yet politicians surely have a duty to lead rather than follow public opinion. Despite that, the Department for the Environment, Food and Rural Affairs quietly shelved plans to bring in annual personal carbon allowances this week, saying the idea was "ahead of its time".

The two main parties will continue to pay lip service to green issues in the run-up to the general election. But something has changed in the past week. Both parties will put saving seats before saving the planet.

If they carry on like this, voters who still put the environment at the top of their list will have to vote Liberal Democrat or Green if they want to change the climate of British politics.

a.grice@independent.co.uk