Having the power doesn’t do any good if they refuse to exercise it.
IIRC, the pretender and his minions have already promulgated a policy to pay ‘prior approved’ expenditures (the welfare state support payments, etc.) in the event the Congress cuts funding. We saw part of it with the (wonderful) gubmint shutdown, not so long ago.
The notion that the Congress holds the purse strings is valid and viable only if they are willing to make use of it, AND take up the ensuing battle to reclaim this Constitutional authority.
A budget would be a nice start.