His colourful attack came at the Nationals federal conference, where the party's differences with the Liberals over the Murray-Darling and parental leave were on display.

Senator Joyce said in his address that Mr Rudd had deserted his own people over the emissions trading scheme.

''He seems to be in the sort of philosophical brothel of ideas. It was just another trick between the sheets for Mr Rudd,'' he said. ''Any virtue can be put aside if the polling pimp tells him to do so.''

The conference opposed the last-resort referendum Opposition Leader Tony Abbott has promised to get power over the Murray-Darling. It also called on the Nationals in government to amend the Commonwealth water act to ensure a balance between environmental needs and those of other users.

A resolution urged ''fair and appropriate'' assistance for stay-at-home parents, and a parental leave scheme that balanced the interests of parents, employers and taxpayers.

Queensland senator Ron Boswell, criticising the government's parental leave scheme that passed Parliament last week, told the conference non- working mothers considered their sacrifice was not being appreciated by the community.

Nationals leader Warren Truss said the generous Abbott parental leave scheme was Coalition policy and the Nationals would vote for it. ''What we do believe, however, is that there's need to do something also to assist mothers who choose to stay at home,'' he told the ABC.