Costello says One Nation now mainstream

Former Howard government treasurer Peter Costello says One Nation has now gone maintstream.

Mr Costello said when he was in office, the government was focused on ensuring One Nation, then viewed as out on the political fringe, didn't become part of the mainstream.

"One Nation has now mainstreamed itself. That's the difference. One Nation now has several senators and the balance of power," He said on ABC news.

Mr Costello said perhaps One Nation had become smarter and more sophisticated.

One Nation wasn't alone and the Senate now features independent Derryn Hinch and members of the Nick Xenophon party.

"Perhaps the major parties left a bit of a vacuum which they came and filled," he said.

Mr Costello said this wouldn't be good for the nation in the long term as it would mean decisions would be horse-traded.

However, the government remained stable and would survive but the quality of its work would be affected, he said.

"My hope is after people have seen this unedifying spectacle for a few years they'll break it at the next election," he said.