Social spending, by a lot, even though only a 5% cut would set the budgets right.
I bet they can also cut a lot of politicians and designated positions, but I'm not that deluded to think they would.
Social spending is redistributive, it reduces wealth inequalities. Shrink it and you make the actual issue worse. I guarantee you this 5% we recover wouldn't be used to balance the budget, but to grant another tax cut to the wealthy. And let's not even mention the consequences of cutting 1/20th of total social spending on human lives, this spending is not just a frivolous expense we can cut in when needed. We've been doing neoliberalism for 50 years, maybe it's time we cut our losses and find something better?
It stops being redistributive if you spend 5% more of what you get in. You're just creating debt without creating a way to pay it down the line. You can either take measures now to pay it or double down and pass it to the next government.