However, I'd like to point out that the budget hawks of yesteryear (Reagan, Simpson, McCain) were at least logically consistent in that they were pro-immigration.
Immigration's positive impact on US fiscal policy is so large that not even right-wing think-tanks can refute it. [1] It raises the fraction of the population currently in the labor force. As a separate, compounded effect, the average immigrant contributes more to the social services pot than they draw out. The bonus to Social Security is even larger because of the undocumented population, which pays payroll taxes but is ineligible for retirement benefits. This effectively foots the bill for 2-3 million American retirees. [2]
So when today's populists peddle nativism while posing as budget hawks, it really fits in nicely with the rest of their bill of goods.
[1] https://www.cato.org/blog/fiscal-impact-immigration-united-s...
[2] https://www.americanprogress.org/article/improving-lives-str...