BARNABY Joyce is under fire from his own colleagues, who say he is a ticking "bomb", and the Federal Government, who have branded him a "freak show".

The Herald Sun reports that Opposition Leader Tony Abbott slapped down his finance spokesman's suggestions that foreign aid could be cut and public servants axed.

There is growing anxiety in Coalition ranks about the high-risk choice of Senator Joyce as a member of the Opposition's economic team.

Economic credibility will be an important election issue, and some say his views put the Coalition's economic credibility at risk.

Others insist he is a breath of fresh air who is cutting through with voters.

Treasurer Wayne Swan described Senator Joyce as "Barnaby Rubble", living in the Stone Age, and Finance Minister Lindsay Tanner said he was "a freak show".

One MP said colleagues cringed when Senator Joyce stumbled over millions, billions and trillions at the National Press Club on Wednesday.

MP said: "There is not a single colleague in the Liberal Party that has any faith (in Senator Joyce). Everyone is just going tick, tick, tick, tick."

Another Liberal said: "If he keeps on going it is going to be a real concern. He can't go around the place talking about (budget) cuts that do not reflect party policy."

A fourth Coalition figure was equally blunt: "Barnaby still operates as a loose cannon. And his comments on foreign investment are seen as too racial."

Senator Joyce was unapologetic when contacted by the Herald Sun, declaring that he would continue to press for savings to rein in debt.

He also denied being counselled by members of the Coalition leadership team.

The attacks came as Labor and the Coalition traded blows in the climate change debate.

Prime Minister Kevin Rudd said Mr Abbott was "all complaint and no solutions". 

Mr Abbott said Labor would impose a "big slug" on households and its claims about his scheme were dishonest.