The latest poll data:

Thirty-one percent of Donald Trump supporters and 24% of President Joe Biden supporters said democracy is “no longer viable” and an alternative system should be tried, according to an October poll from the University of Virginia’s Center for Politics

The poll surveyed 2,008 registered voters from Aug. 25 to Sept. 11 and has a margin of error of plus or minus 2.2 percentage points.

Other key findings:

When asked whether it is acceptable to employ violence to stop political opponents from attaining their goals, 41% of Biden supporters and 38% of Trump supporters said yes.

30% of Trump supporters and 25% of Biden supporters said elections should be suspended in times of crisis.

41% of Trump supporters and 30% of Biden supporters said they favor either conservative or liberal states seceding from the union.

Nearly half of Biden supporters, 47%, and 35% of Trump supporters said the government should restrict the expression of views “considered discriminatory or offensive.”

Plenty of democratic countries restrict speech more than the U.S., and are still civilized countries, so that's less worrisome.  The favorable attitude towards violence against one's political opponents, which is bipartisan (!), is much more alarming.