For the first time since he became prime minister, there are more voters unhappy than happy with the performance of Malcolm Turnbull.

The findings, in the Newspoll published in The Australian on Monday, found 44 per cent of those surveyed were dissatisfied with Mr Turnbull's performance (up 3 points in the past fortnight), compared with 39 per cent who were satisfied (down five points).

A Fairfax/Ipsos poll published last week also found a drop in Mr Turnbull's approval rating but to a much smaller extent.

More survey respondents are dissatisfied than satisfied with PM Malcolm Turnbull. Chris Hyde

Mr Turnbull is still viewed more favourably than Opposition Leader Bill Shorten. The Newspoll found only 28 per cent of voters are satisfied with Mr Shorten's performance (down two), compared to 52 per cent dissatisfied (down three).

The shift comes as the government agreed to toughen laws on the abuse of market power by big business while Liberal Senator Arthur Sinodinos admitted the Turnbull government did not have the money for major tax reform but argued that cutting corporate tax rates would benefit workers through higher wages.