The NDP is proposing toughening up the ethics commissioner's role, and banning MPs and senators from sitting on corporate boards.

MPs Peter Julian and Françoise Boivin also told a news conference Thursday in Ottawa that there needs to be a common structure for posting expenses.

"We are not in favour of some kind of individual system, a free-for-all, where every MP posts different expenses at different times," Julian said.

The party also wants to ban MPs and senators from "double-dipping" by charging speaking fees or receiving other payment "for work that is part of their job."

The NDP would also like to see the existing ethics rules enshrined in law, and want to give ethics commissioner Mary Dawson the power to "administer real penalties when politicians break the rules."

As it stands, the commissioner can't even impose fines on MPs who fail to comply with the conflict of interest code.