Liberal Democrat leader Sir Menzies Campbell has hailed his "green" tax proposals as the "most radical ever from any major UK political party".
Sir Menzies is hoping to win a vote on new tax proposals
He said he wanted to "shift the tax burden from hard working people and on to the polluter".
Sir Menzies was speaking at a rally to launch a national campaign at the party's annual conference in Brighton.
But he faces a battle with party activists to persuade them to back the proposals in a vote this week.
Sir Menzies said: "Liberal Democrat values and Liberal Democrat leadership are needed if Britain is to play its proper role in dealing with climate change.
"The green tax switch is not about more tax, it's about greener tax and fairer tax.
"It will change polluters' behaviour and it will help in the battle to safeguard our planet for future generations. It will also shift the burden from had working people and on to the polluter."
The party's environment spokesman Chris Huhne said the Green Tax Switch campaign was the biggest it had ever run.
"We will be delivering over a million leaflets up and down the land, as well as holding countless events to encourage the British people to make the Green Tax Switch and halt climate chaos."
The proposals include:
- Increase road tax on the most polluting cars to £2,000Increase tax on air travel
- Extend the Climate Change Levy across the whole economy
- Take low earners out of the tax system
- Cut taxes on middle income earners
Sunday's opening conference rally also heard from ecologist and author George Monbiot, who said he would be publishing new figures next week on the scale of the climate threat.
The UK Government is currently committed to cutting CO2 emissions by 60% by 2050.
But Mr Monbiot said the 60% reduction must be made by 2030 across the globe - and if the UK was to take its fair share internationally, it needed to reduce emissions by 87%.
"Without cracking this, you can forget about the other issues," he said.
Parts of the Lib Dem leadership's tax package are facing opposition from within the party - and Tuesday's vote on the plans is seen as a crucial test for Sir Menzies.
Senior MP Dr Evan Harris is leading the fight to restore a policy - on incomes above £150,000 - which he says has proved very popular on the doorsteps.
Another group of activists is challenging the proposal to make any changes to tax policy revenue neutral - raising no extra money for public spending.
Sir Menzies played down the potential fall-out of an embarrassing defeat for his leadership in Tuesday's vote on the issue - insisting it was not a "High Noon" moment.
But Treasury spokesman Vince Cable warned that colleagues would "all be facing some difficulty" if the crunch ballot was lost.
Dr Harris claimed growing support for his campaign as the conference got under way, including from several MPs and peers.
Frontbenchers Sandra Gidley and John Leech are among the names, as well as former members of the "shadow cabinet" Norman Baker, Phil Willis and Baroness Jenny Tonge.
The amendment says that retaining the 50p rate on incomes over £150,000 would allow more people to be taken out of the tax system.
Dr Harris said: "More and more people now recognise that the 50p top-rate amendment makes the tax package even fairer, makes our intentions much clearer and builds on the proposals rather than simply harking back to our 2005 manifesto policy."