Not secession. That’s so 1860.
Ejection! Kick them out of the Union, let them manage their own affairs as stupidly as they like, and accept the secession of those regions in the blue states who want out of their respective nut houses. They can keep DC and choke on it. The new capitol would be in Osh Kosh, Wisconsin, just because it has a nifty name.
Even easier, disenfranchise the "sanctuary cities".
Arrest those local officials at the top who are aiding and abetting the illegal aliens.
Deny them the federal grants (RAT gravy train)