CANBERRA, AAP – Controversial workplace reforms could still be voted on in parliament next week despite the industrial relations minister being on leave.

Christian Porter, who is also the attorney-general, is taking time off after being accused of a historical rape, which he strenuously denies.

Prime Minister Scott Morrison has backed Mr Porter’s temporary replacement Michaelia Cash to advance the bill through the Senate.

“I have absolute confidence in Michaelia,” he told reporters in Sydney on Tuesday.

“Minister Cash has had quite a bit of experience getting important industrial relations legislation through the parliament in the past.”

Senator Cash’s stint in charge of workplace relations was mired in controversy after her staff tipped off media about raids on union offices.

Business groups have urged the government to forge ahead with trying to pass the bill with next week’s Senate sitting the last before the May budget.

Crossbench senators have indicated a willingness to vote on the legislation next week if a deal is reached but that appears unlikely.

The definition of casual employment and the process for those employees to convert to permanent roles remain key sticking points.

The coalition has dumped the most contentious part of the bill, which would have given the industrial umpire more scope to allow enterprise agreements that don’t meet the better off overall test.

The government needs three of the five crossbench votes to pass the legislation, with Labor and the Greens fiercely opposed.

The industrial relations omnibus bill also makes changes to enterprise bargaining, wage theft penalties, long-term pay agreements on major projects and awards.