Only if those civilians are unarmed. Name one instance where an armed population was overwhelmed by a military force so much smaller than itself. It has never been done.
There aren't any.
You are probably correct in your general conclusion that there are too many armed civilians for the Federal government to sustain a campaign of forcible subjugation,
That will not stop the Progressives from trying.
Progressives don't do math. They are grabbing for the gold ring of permanent rule over this country, and with every failure, they simply redouble their efforts. They will continue in this direction until they are removed from any positions of power. And they will not step down voluntarily.
This sort of miscalculation guarentees that events will go badly for everyone. There are plenty of contemporary examples of how this develops. Check the story in Yugoslavia, Venezuela, Bolivia, Argentina, Mexico, Egypt, or Syria for some of the more extreme details.
There is a wealth of learning experiences in those stories. Of course none of that could ever happen here...
"I think they overestimate their chances" (Gen Moff Tarkin).