Got it exactly backwards.
Without tax reform any spending cuts you made are meaningless. Reagan cut and cut and cut, and by the end of his Presidency the spending was ALL back at higher levels then when he came in.
Unless you fundamentally attack the root issues, like the tax code, any “reform” the next President implements will be stop gap and transitory.
Reagan cut taxes (from obscene levels for the investor class) but wasn’t able to rein in spending. His policies increased revenue coming in, but couldn’t contain spending.