An Essential Research poll completed two days ago also found that four in 10 people think Labor would have more chance of winning the election if it changed leaders.

Only 37 per cent said Kevin Rudd was the best person to lead Labor to the election.

Nearly half (47 per cent) believed the Liberals would do better if they changed leader; fewer than three in 10 said Tony Abbott was the best to lead the Liberals to the election.

Ms Gillard has dramatically narrowed the gap between her and Mr Rudd as better prime minister.

Her support has risen from 26 per cent in February to 33 per cent now, while Mr Rudd's has fallen from 45 per cent to 36 per cent.

Ms Gillard and Mr Rudd each lead Mr Abbott as better PM by an almost equal margin when put head-to-head against him. Ms Gillard is ahead of Mr Abbott 50 per cent to 32 per cent, while Mr Rudd leads him 47 per cent to 30 per cent.

The poll comes amid widespread criticism of Mr Rudd's leadership but no sign of a move against him. Ms Gillard has repeatedly insisted she will not challenge for the leadership.

The online poll of 1066 people between June 15 and June 20 had Labor leading on a two-party basis by 52 per cent to 48 per cent, with the Coalition on a primary vote of 40 per cent, Labor on 38 per cent and the Greens 11 per cent. The Labor primary vote is higher, and the Greens' vote lower, than in other recent polls.

One quarter of Liberal voters thought the Liberals would have a better chance with another leader.

The Liberals have launched a new ad labelling the Prime Minister Kevin O'Lemon. Running on Sky TV and the internet, it shows a lemon transforming into Mr Rudd.

It says: ''You think something is going to be great, and you just can't wait to get it. But don't you hate it when you start to realise it's not what you thought it was? It looked good, it sounded good, but it's all gone sour. It's a lemon, Kevin O'Lemon - one big disappointment.''

On the ABC's Australian Story Gillard profile last night, former Queensland premier Peter Beattie said Mr Rudd ''in the long term should pave the way for Julia to become the prime minister. I'm not trying to undermine Kevin Rudd at all. It's the right thing to do for the country.''

Meanwhile, outspoken Liberal backbencher Wilson Tuckey came under fire when he linked the plane crash in Africa to the mining tax.

He said he did not want the tax to be portrayed as the cause of the tragedy but ''we have a tragic example of where the mining industry is now focusing its attention''.