Hospitality, retail, health and community sector workers will protest from 7.30am, using social media, billboards, “high visibility stunts” and wobble-boarding to get their message across.

They’ll be targeting the marginal federal seat of Boothby. Workers will be stationed at various intersections across the electorate including Greenhill Rd and Anzac Highway and Diagonal and Brighton roads.

SA Unions secretary Dale Beasley expected up to 10,000 workers to take part.

“Workers are taking action because Scott Morrison has delivered nothing but huge steps backwards for working people,” Beasley said.

“We expect Scott Morrison will use the federal budget as a last chance to spin his way out of trouble before the federal election, and South Australian workers have had enough of it.

“Scott Morrison’s record for South Aussie workers is appalling. We have skyrocketing rates of underemployment and insecure work. We’re experiencing the highest ever rate of workers requiring more than one job to make ends meet. Most working people do not take multiple jobs by choice. This is a clear illustration of the toll that insecure work is taking on South Australian workers.”

Josh Frydenberg will hand down his fourth budget as treasurer tonight, with the government hoping to use it as a political springboard for the upcoming federal election.

The federal budget is set to focus on the rising cost of living, driven by increases in petrol and grocery prices, with relief measures such as a temporary cut in the fuel excise being touted.

While delivering immediate relief, Frydenberg is also pitching the budget as a long-term economic plan providing skills, building more roads, funding national security, driving down the cost of energy and rolling out essential services.

Prime Minister Scott Morrison is expected to trigger a May election after letting the dust settle on the coalition’s post-budget pitch.

As petrol prices pass $2 a litre, the fuel excise is largely expected to be cut temporarily by 10 to 20 cents per litre for six months.

The government has hinted at “targeted and proportionate” cost of living relief, particularly helping low and middle-income earners.

Frydenberg has aimed to emphasise the “fiscal dividend of a stronger economy” ahead of the budget, with the budget deficit expected to be lower than the $98.9 billion estimated for 2022/23 in last year’s mid-year budget review.

Swathes of money have already been set aside for infrastructure projects, with more than $120 billion to be spent over the next decade.

Opposition Leader Anthony Albanese will deliver his budget reply speech on Thursday night.

• With AAP