Liberal Democrat leader Nick Clegg pleaded with voters today to trust his party to "deliver the fairness that people want".
Mr Clegg said the Lib Dems had a track record of good judgment, having been the first party to warn about the banking crisis.
And he flagged up the credentials of Treasury spokesman Vince Cable, describing him as "the best batsman around".
But he appeared to dismiss suggestions that Mr Cable could become chancellor if a hung parliament is returned after May 6, saying: "It doesn't work like that - we work as a team."
Speaking to GMTV, the Lib Dem leader accused both Labour and the Tories of making "buy now, pay later" tax pledges.
And he said: "I think the key thing in this election is who do you trust to deliver the fairness that people want.
"And I think on, for instance, the way we have said very clearly, before any other party did, that the greed of the bankers in the City of London was going to lead to disaster - that's an example of trusting us to have the right judgment."
Put to him that Mr Cable enjoyed a higher profile among voters, Mr Clegg said: "I'm absolutely delighted that my close friend and colleague Vince Cable is, if you compare him to Alistair Darling and George Osborne, is by far the most trusted and authoritative."
And he said: "If you want Vince Cable in No 11, vote for the Liberal Democrats."
Pressed on whether Mr Cable might become chancellor if the Lib Dems hold the balance of power after the election, Mr Clegg compared his Treasury spokesman to Manchester City footballer Carlos Tevez, who moved across the city from arch-rivals Manchester United.
He said: "I don't think Vince is going to be in the sort of Carlos Tevez school of transfers from one team to another.
"We work as a team, the Liberal Democrats work as a team. I'm very proud, as the captain of the Liberal Democrat team - a bit like the captain of a cricket team - that in Vince Cable we have the best batsman around."
Mr Clegg continued his attack on Conservative tax policies, saying David Cameron's party had drawn up a "huge shopping list of tax bribes".
The Lib Dem leader has been critical of the Tories' plan to scrap most of Labour's planned rise in National Insurance, claiming Mr Cameron would have to raise VAT to 20.5% to pay for it.
The Conservatives deny this, saying the move will be funded by government efficiencies, and Mr Clegg was asked if he was calling Mr Cameron a liar.
He replied: "I'm saying the Conservatives aren't being straight with people about how on Earth they are going to pay for it.
"I think both Labour and the Conservatives in this debate are presenting us with a debate about tax which is 'buy now, pay later'.
"The question in politics is not whether you dislike taxes - we all dislike taxes - it's how do you pay to keep taxes down?"
Mr Clegg said his party would ensure people paid no income tax on their first £10,000 of earnings, funded by closing "huge loopholes" in the tax system.
He also pledged to bring down class sizes in schools to give children a "fair start in life", offering: "£2.5 billion extra for schools every year by cutting spending elsewhere in government."
And he said the NHS would be "very safe" in Lib Dem hands, with bureaucracy cut to protect frontline services.
Earlier the Liberal Democrats said they would stop banks charging excessive penalties for customers who go over their overdraft limit.
The party's manifesto for consumers will also contain measures to limit charges for bouncing a cheque and cap the interest rates on credit cards.
Mr Clegg said banks should not be allowed to "profiteer" from people making small mistakes.
The Lib Dem leader will launch his party's campaign in Wales during a visit to Cardiff today, before heading to Birmingham and Leeds and ending the day in his Sheffield constituency.
Outlining his plan to boost the power of consumers, Mr Clegg told reporters in Cardiff he would take on the "vested interests" in the business world.
He said: "Consumers still get a seriously raw deal in this country.
"We have still got far too many vested interests in the business world who are ripping people off."
He said excessive bank charges for straying over an overdraft limit or bouncing a cheque were "seriously out of order".
And he said low-cost airlines should be open about the total cost of flights with "no hidden charges".