The government should learn from the Liberal Democrats and look at more ways to tax Britain's top earners, Treasury Minister Angela Eagle says.
The Lib Dems want to tax the super-rich.
She spoke out during a fringe meeting at Labour's conference in Bournemouth, which was joined by senior Lib Dems Vince Cable and David Laws.
Lib Dem leader Sir Menzies Campbell wants to tax the super-rich to fund tax cuts for the rest of the population.
Sir Menzies has argued that the wealthy have done "too well" under Labour.
He used last week's Lib Dem conference to unveil tax policies that he claimed would help 90% of the population.
These included lowering the basic rate of income tax by 4p in the pound to 16p, calling for the abolition of council tax and voting to increase "green" taxes, including replacing air passenger tax with a tax on flights.
At a Centreforum and Fabian Society fringe event at Labour's conference, Ms Eagle was asked if her party faced a "challenge" from its opponents when it came to talking about the top end of the tax scale.
She replied: "Yes. And I for one hope we're going to do a bit of talking about that."
During the debate, Sir Menzies deputy Mr Cable criticised Prime Minister Gordon Brown's efforts to create a "government of all the talents" by recruiting opposition politicians.
Although Mr Brown's attempts to recruit former Lib Dem leader Lord Ashdown to his cabinet were rejected, he has enlisted the help of several senior party members in advisory roles.
Mr Cable said: "I am concerned about what I would regard as big tentism - this attempt to get everybody into the same fold.
"I think it is an attempt to create - in the nicest possible way - a one-party state."
He likened Mr Brown to Jomo Kenyatta, former president of Kenya, for whom he once worked and who engaged in big tent politics.
"It was about sucking out of opposition parties any potential source of dissent - giving them a role; giving them a state regardless of colour or tribe or ideology," he said.
"It was superficially very attractive but ultimately it is dangerous because it destroys constructive opposition and we are very concerned about it for that reason."