The Federal Government is one step closer to passing its key industrial relations legislation, with Pauline Hanson's One Nation confirming its four senators will vote in support of the Coalition's bills.

Key points: Malcolm Roberts to outline One Nation's commitment to supporting ABCC bill

Malcolm Roberts to outline One Nation's commitment to supporting ABCC bill Labor, Greens oppose ABCC and Registered Organisations bills

Labor, Greens oppose ABCC and Registered Organisations bills NXT is yet to reveal how it plans to vote, raises concerns about ABCC bill

The party's Queensland Senator Malcolm Roberts used a speech today to outline One Nation's commitment to supporting the Australian Building and Construction Commission (ABCC) and Registered Organisations bills that triggered a double dissolution election.

"Let me confirm our united party is inclined to support the Government's ABCC and [Registered Organisations] legislation as it stands, because the bills promote freedom," Senator Roberts said.

Labor and the Greens oppose the bills, so the Government, which has a majority in the House of Representatives, needs the support of nine of the 11 Senate crossbenchers to pass them.

The Nick Xenophon Team is yet to reveal how its three senators will vote, after raising concerns about aspects of the ABCC bill.

The Government is also trying to secure votes from David Leyonhjelm, Derryn Hinch and Bob Day's eventual replacement. Jacqui Lambie has previously opposed the bills.

In excerpts of Senator Roberts' address, provided to the ABC and delivered to conservative industrial relations organisation the HR Nicholls Society, he said the party had consulted widely on the legislation.

"Every bill put before the Senate is scrutinised on its merits by our party, we interrogate its instigators, we listen to our crossbench colleagues about their proposed changes and we listen to the people's needs," the excerpts read.

"If anyone comes to chat about these bills we will ask them: if there is a problem in Australia's industrial relations culture that needs to be fixed, and if you oppose this proposal, what alternative legislation or mechanism would you propose?"

Senator Roberts this week revealed he had seen secret volumes of the final report of the Trade Union Royal Commission as part of the Government's negotiations to reinstate the construction watchdog.

Before the election, the Government said it would consider showing key crossbenchers the volumes to win over their support for the ABCC legislation.

Senator Roberts told a Senate Estimates Committee hearing he had to sign a confidentiality agreement to view the documents.

Labor senators said they had not been given the same opportunity.