Plans to drug test unemployed welfare recipients could be pushed back at least several months, with just weeks remaining to secure a parliamentary deal.
Social Services Minister Christian Porter has signalled he may be willing to separate the trials from a broader welfare bill if it means other changes can clear parliament before Christmas.
"I wouldn't want to sacrifice the bulk of that (bill) in terms of timeliness, while we are still negotiating around drug testing," Mr Porter told the National Press Club in Canberra on Wednesday.
The Turnbull government wants to drug test 5000 welfare recipients in a pilot across three trial sites from January.
Anyone who tests positive would be shunted onto cashless welfare cards, while those who fail more than once would be referred to medical professionals for treatment.
But with Labor and the Greens dead against the idea, Mr Porter must court support from the Senate crossbench.
And with just two sitting weeks remaining until the Senate adjourns for the year, the time for negotiations is quickly running out, with at least one of those weeks to be spent dealing with same-sex marriage legislation.
Further complicating negotiations is the ever-changing face of the Senate, helped along by the dual citizenship fiasco.
Former senator Nick Xenophon, whose bloc of three votes in the upper house will be crucial, offered the drug testing trials conditional support before exiting the building.
Another of his party members, Skye Kakoschke-Moore, resigned on Wednesday after discovering she was a dual citizen.
"The complexion of the Senate is changing rather rapidly and I'm always willing to talk to new senators about this and I think there is a mounting case to let us have a go at this," Mr Porter said.
The minister pointed out the drug testing trials took up about seven of 200 pages in an omnibus welfare bill.
The legislation would also introduce a demerit point system for people who persistently dodge job seeking obligations, tighten exemptions around drug and alcohol dependence and fold seven different existing payments into one.
If the government were to extract the drug testing trials, the resulting separate piece of legislation would probably have to wait until parliament returns in February.
