As a recovering big "C" conservative... I'll take a stab.
We are poised to hit a couple of "not great" milestones in the next year or so. We will in the near future 1) cross the 100% debt/GDP threshold and 2)have an annual outlay greater than $1T for interest payments on the national debt. The $1T factoid is pretty much meaningless, except for the fact that we now have more than $1T that is not available to provide actual goods and services to our citizens. The 100% debt to GDP ratio is concerning because it could be a trigger point for credit rating agencies to downgrade the US Govt's credit rating and shift to more negative outlooks.
The biggest concern is that interest as a share of the budget keeps growing. In 2024, 13% of the Federal budget went to service the debt. By 2035, that will be up to 16% ($1.783T). Again... that will be 16% of our budget not providing benefits to our citizens, because no one has the political will to keep spending in line with revenues.
How far can we go and how big can the problem get before it becomes critical? We don't really know... but we REALLY don't want to find out.