Prime Minister Malcolm Turnbull has ceded the Coalition's lead in an opinion poll for the first time since the leadership coup, when he said Tony Abbott's poor performance in the same survey justified the change.

Newspoll, published by News Corp late on Monday night, had the Labor party leading the Coalition 51-49 on a two-party preferred basis. Mr Turnbull's personal ratings were down four points, while Labor leader Bill Shorten's by improved six points, which is outside the margin of error.

Labor's primary vote was up two points to 36 while the Coalition's was down two points to 41, compared to the previous fortnight's poll. Both changes are within the margin of error. Just one month ago the Coalition and Labor were neck-and-neck at 50-50.

Queensland backbench MP Ewen Jones told Fairfax Media he believed the budget would answer a lot of questions about the government's direction and said he did not believe claims Mr Shorten was "unelectable."