Influential crossbench MPs will push for major improvements to the operation of Parliament after the election, including truth in political advertising laws and a code of conduct for politicians.

In what could form an opening demand in negotiations with the Coalition or Labor in the event of a hung parliament after the May election, MPs Helen Haines, Rebekha Sharkie and Zali Steggall have signed on to a plan for ministerial diaries to be routinely made public, more time for debate of private members’ bills and a ban on party fundraising inside Parliament House.