Parliament will resume on Monday for the final two sitting weeks of the year before going on a break until February. The government has listed its Registered Organisations Commission and Australian Building and Construction Commission bills - both triggers for the early July election - for debate in the Senate this week.

The government is working overtime to pass the bills because success would demonstrate its ability to pass contentious legislation through the Senate and help justify the early election.

It is confident of beginning the week with a win on the Registered Organisations bill, which would impose the same disclosure and transparency obligations on union officials as company directors. It would also increase penalties for union leaders involved in fraud.

Workplace Relations Minister Michaelia Cash was meeting with Independent Senator Nick Xenophon on Sunday afternoon to discuss the bill and is expected to meet with Derryn Hinch on Monday.

Senator Xenophon is pushing the government to increase whistleblower protections to win his support.

Liberal Democrat Senator David Leyonhjelm, who said he has acted as a "go between" for the government and Labor on the issue, said he expected an amended version of the bill to pass with Labor's backing. "I think it will be amended sufficiently so both sides can support it," he said.

Labor has voted against the bill twice previously and has called for the Australian Securities and Investments Commission (ASIC) to be given oversight for unions rather than a new bureaucracy.

Labor workplace relations spokesman Brendan O'Connor said it was "possible" the registered organisations bill will pass with Labor support if the government makes amendments.

The government is expected to face a bigger challenge with its bid to reinstate the Australian Building and Construction Commission. Senator Hinch and the Nick Xenophon Team are pushing for substantial amendments while Senator Leyonhjelm is looking for a separate trade-off to secure his vote for the industry watchdog.

Prime Minister Malcolm Turnbull has said the government will only bring the bills on for a vote when it is confident of victory.

"The ABCC involves a reduction in liberty because of its coercive powers," Senator Leyonhjelm said. " I would only be induced to vote for it if the government increases liberty somewhere else."

He said: "We haven't reached a landing point on the ABCC yet, I don't think they have the numbers."

Pauline Hanson's One Nation block is expected to vote for both bills, but this could be complicated by West Australian Senator Rod Culleton who will appear in the High Court to defend his eligibility to sit as a Senator. Senator Culleton has indicated a more pro-union position than some of his colleagues, sparking confusion about how he will vote.

Senator Xenophon said he did not expect the ABCC bill to be voted on this week. "We don't want to rush it," he said.

A spokesman for Senator Hinch said he still had concerns about the ABCC bill, including the use of 457 visas, the impact on apprentices and whistleblowers.

The government says the ABCC - introduced by the Howard government before being scrapped by Labor - would discourage lawlessness on construction sites and boost productivity. But Labor says it treats construction employees unfairly by denying them the same rights as other workers.

The government also faces a battle to pass its legislation to create a new lifetime ban on asylum seekers who arrive by boat. Senator Hinch is opposed and the Nick Xenophon Team will treat it as a conscience issue, making it harder to predict how its three senators will vote.