Crossbench senators have rejected Malcolm Turnbull's idea of a brokered deal to reinstate the building industry watchdog.
The prime minister has recruited his "old friend", South Australian Family First senator Bob Day, to convince six crossbenchers to support the Australian Building and Construction Commission (ABCC).
On Tuesday, Mr Turnbull praised Senator Day for his leadership while assuring Australians that the ABCC was not union-bashing but economic reform.
"If Bob can present six senators who are prepared to support the legislation and if the amendments they propose are ones that are consistent with the purpose and intent of the bill, and don't weaken it, then we would consider them," Mr Turnbull said.
Reflecting on the bill's chances, the prime minister said: "We'll see what happens."
Independent senator John Madigan said Senator Day had "no authority" to negotiate with the government on his behalf.
Australian Motoring Enthusiasts Party senator Ricky Muir wants to negotiate directly with the prime minister.
"I remain of the feeling that the government is not genuine about getting the legislation passed and would rather leave it unamended," Senator Muir told AAP.
Independent senator Jacqui Lambie said she would only support a national anti-corruption body that covered not just construction but banking, insurance and government officials.
"Bob Day is free to make decisions for himself and his own state - but the problem for Bob is that his voting record shows he should just join the Liberal party," Senator Lambie said.
Liberal Democrats senator David Leyonhjelm said the idea that Senator Day could round up six crossbench votes was "insane" and event Senator Day himself would agree.
"That's not how you do it on the crossbench ... we'd be lucky to agree on what day it is," Senator Leyonhjelm told Sky News.
Independent senator Glenn Lazarus accused Mr Turnbull of attempting to "sweeten up" other crossbenchers, while confirming he wanted a broad-ranging commission.
Palmer United Party senator Dio Wang said he had received a "cold" response from the government to his ideas in recent weeks, despite earlier signs of listening.
Senator Cash said any proposed changes to the ABCC bill would have to be presented by a bloc of six crossbenchers.
"When you negotiate with individuals, you might secure one vote and then you have to go and have that conversation another seven times," she said.
Both houses of parliament have been recalled for a three-week sitting from April 18 to deal with the ABCC and other union-related legislation.
If the bills aren't passed, they will become a trigger for a double-dissolution election on July 2.
Labor believes Mr Turnbull is now "running scared" from dissolving both houses of parliament.
"Does he want an election or not?" shadow treasurer Chris Bowen said.
