A fight over penalty rates will cloud the federal government’s agenda as it tries to keep parliament focused on helping parents with childcare fees and repairing the budget.

Labor wants to capitalise on the Fair Work Commission’s decision that some Sunday penalty rates should be cut, with leader Bill Shorten flagging to parliament he wants to stop that ever being implemented.

More than 600,000 hospitality, retail and fast food workers are expected to lose money after the commission’s ruling.

“I’ll be standing up for these workers in the parliament all week,” Mr Shorten told AAP.

“The prime minister needs to do the same. These people have bills to pay and families to support, and every single one has less money in their pocket as a result of this dreadful decision.”

Both Labor and the Greens will introduce bills in coming weeks to change the Fair Work Commission’s rules to ensure last week’s decision is never implemented and penalty rates can’t be dropped in the future if it results in cuts to take-home pay.

Malcolm Turnbull and business groups have called for all parties to respect the decision of the independent umpire.

The Turnbull government is keen to get its “omnibus” welfare bill and business tax cuts through the lower house by the end of the week, allowing the Senate to debate them at the next sitting starting on March 20.

Finance Minister Mathias Cormann has not given up on getting as much of the omnibus bill through parliament as possible, despite opposition from key Senate crossbench blocs likely dooming it.

“These conversations are still live, they are still ongoing, I’m certainly not prepared to put up the white flag,” Senator Cormann told Sky News.

The bill contains a range of welfare cuts as well as an overhaul of childcare subsidies they are designed to fund.

It’s probably destined to be picked apart as the government seeks to salvage at least some measures.

Senate estimates hearings throughout the week will probe the whole operation of government, with Labor seeking answers on Australia Post executive salaries, pension and welfare cuts and the US refugee deal.