From the comments
The “Primary Budget Surplus” is an ivory-tower concept that is counterproductive in the real world. A sophisticated lender or rating agency is concerned about the borrower’s ability to cover ALL of his expenses, and especially his loan repayments. The fact that the borrower could be solvent if he didn’t pay back his loan is not reassuring. In fact, this “primary budget surplus” condition puts the borrower in a moral hazard situation, where he might be better committing an Argentina-style default.