Xenophon warns against Senate horsetrading

Independent senator Nick Xenophon has warned his fellow crossbenchers against horse-trading, as some of them prepare to punish the government over voting reforms.

Family First's Bob Day and Liberal Democrat David Leyonhjelm have withdrawn support for legislation restoring the building industry watchdog after the government announced changes that could spell the end of micro parties in the Senate.

"The problem with horse-trading is that sometimes you can end up with a donkey or even worse make an ass of yourself," Senator Xenophon told reporters in Canberra on Thursday.

"I think it's very important that if you have a position on a bill it is consistent. If you change your position - which you are entitled to do so - it is on the basis of the facts changing, the evidence changing," he said.

Senator Leyonhjelm hit back, labelling Senator Xenophon as the "master horse-trader" of parliament.

"He is the horse-trader par excellence."

The Liberal Democrat said he had given the government the benefit of the doubt on reinstating the Australian Building and Construction Commission, but subject to a sunset clause.

"In exchange I get a nasty sneak attack on my right to exist ... in the Senate."