The Coalition has fallen behind Labor for the first time since Malcolm Turnbull took over as Prime Minister, according to the latest Newspoll.

The latest polling, published today in The Australian, has Labor leading the Coalition after preferences 51 per cent to 49 per cent, an increase of two points on the previous polling.

The result does fall within the poll's 2.3 per cent margin of error.

The Coalition's primary vote fell to a six-month low of 41 per cent, down five points since the start of the year, while Labor's primary vote rose two points to 36 per cent.

Mr Turnbull brushed off repeated questions about the polling, telling reporters he would leave the commentary to the media.

Cabinet Minister Christopher Pyne said the Federal Government had a "messy week" in the lead-up to Friday's meeting with premiers and chief ministers, culminating in the withdrawal of the Prime Minister's income tax proposal.

Mr Pyne told the ABC voters had been influenced by the debate on income tax.

"If you look at the poll between who people want, Malcolm Turnbull or Bill Shorten, Malcolm always leads Bill Shorten basically at two to one, at least two to one," he said.

"So sure, polls come and go and today's Newspoll is a reflection of the messy week."

Turnbull honeymoon over according to Labor

Liberal Senator Michaelia Cash backed Mr Pyne's comments, telling the ABC, "When you deal with difficult issues, it can sometimes get a little bit messy".

Today's polling remains above the Coalition's results in September, when Mr Turnbull cited poor polling — losing 30 Newspolls in a row — in his ousting of his predecessor Tony Abbott.

But Labor Senator Sam Dastyari said the results were a sign Mr Turnbull's popularity was faltering.

"The honeymoon that Malcolm Turnbull first enjoyed when he became leader was never going to last," Senator Dastyari told the ABC.

"This is a bad government with bad policies that wants to do bad things and as a result it will be a very, very tight, close election."

The latest results are based on 1,743 interviews conducted between Thursday and Sunday last week.