Problem: Around the time of the Civil War, the people of each state tended to have a much stronger loyalty to their individual states than they do today. Most people today do not consider themselves citizens of their states, just citizens of the United States.
Even if we could scrounge up enough numbers to push for secession in state governments, the federal government would respond with military force to "secure" states. The seceding states may or may not be able to get their own National Guard to stick with them in principle, but the biggest problem is that the average American has been taught to worship the US military. This includes National Guard members, and it includes the vast majority of US citizens.
When American troops march down the streets of seceding states to "secure" their position in the state and "keep order," who is actually going to violently resist the same troops they have been indoctrinated to love and worship? Besides the whole indoctrination thing, some of these troops could even be their own friends, sons, daughters, brothers, sisters, husbands, and wives, from the very same state. If you think about it realistically, the military is extremely unlikely to just come in "guns blazing," destroying everything in sight and provoking a defensive response. Instead, they will come in under the guise of "peacekeepers" and "law enforcement," and as far as I can tell, the only way for a seceding state to physically repel the invading army would be to fire the first shot.
Who the hell would actually fire that shot? As far as I see it, nobody would, or at least nobody would follow up on it. Nobody wants that kind of horrific bloodshed between countrymen, and I just do not see it happening. Even guerilla warfare by small bands of rebels would not actually work to make secession succeed, because by that time, the military would have replaced the state governments with essentially provincial governments, which have "changed their minds" on the issue of secession. The laws that ordinary people follow would once again be federal laws (specifically martial law, too).
In short, there is really only one way for secession to ever succeed: That is to get the majority of troops on our side too, so that when the time for secession comes, the United States military falls apart internally. This by itself is a tall order, because the United States military does everything it can to turn the troops into nothing more than obedient robots.