Labour MP Sue Moroney's looking to pressure the Government into backing her paid parental leave Bill.

Her Member's Bill, due to have its second reading in Parliament tonight, would extend paid parental leave entitlements from 18 to 26 weeks.

Ms Moroney said tomorrow's Budget must deliver 26 weeks paid parental leave by April 2018 and anything less will short-change families.

"If they do anything less than what my bill proposes then clearly that's just cheap politics and short changing families for political reasons."

Workplace Relations and Safety Minister Minister Michael Woodhouse, who's responsible for paid parental leave, said the Government's satisfied it's got the balance right now.

"There's always more we could do but it comes down to the trade offs we have with other government priorities. We have a range of things that we do for new parents and I think we got that balance right."

However Ms Moroney is expecting a paid parental leave extension in tomorrow's Budget.

"I think if they weren't preparing to extend paid parental leave in the budget they would have absolutely ruled it out by now. They haven't done that, so we believe they will be looking to increase paid parental leave."