The Republicans are basically foreshadowing a debt ceiling showdown. As is, $31 trillion of debt is a talking point, not a problem. It's actually really poor economics to have a balanced budget, because often times the spending pays for itself through growth. However, the projected $150 trillion in unfunded liabilities could break us. We can't have too large of a percentage of our population collecting Social Security/Medicare and not contributing much in taxes. Really the only thing the only the government must pay for is interest. Everything else could theoretically be borrowed. If the interest exceeds tax revenues (or the world expects that it will) we will have an economic disaster. Interest rates would skyrocket higher as our treasuries would become junk bonds and countries around the world would push to remove us as the reserve currency. The government would either face an inflation crisis or default. The easiest/smartest way to address this in the near-term is to increase immigration in order to get a higher labor force participation rate and more workers paying taxes.
The proper to look at this is debt to GDP. There is no magic recipe either. We are the world’s reserve currency and market of choice. We must grow. If debt is your thing and you’re talking about cutting spending instead of how to increase gdp growth you are totally clueless.