"Let the Republicans and the Democrats split the liberal vote!"
Yes, and that is precisely what WOULD happen.
There are plenty of Democrats who are conservative, but who will not vote for the Republican party because the GOP is the party of the country club, etc. The partisan rancor is so deep that people may hate their own party real bad, but they will never, ever, ever vote for the OTHER hated party.
Reagan Democrats actually bit the bullet and came over, but many many conservatives, at least social conservatives, remained behind in the Democratic party because they cannot stand country-club GOP elitism and never will, or because Lincoln burned Savannah, or whatever.
A third party that is American and Conservative in name, and doesn't pretend that it's the "heir of Lincoln" or any some such, which is conservative and NOT Republican, will get conservatives who were Democrats who cannot ever consider voting for a Republican as a quasi-religious proposition...that one doesn't make deals with the Devil.
If it were started on a place like FR, and then picked up and championed by some of the talk radio media, it would grow, swiftly. It would not become the majority party, and would not win the Presidency, but it would certainly win some seats in the national legislature, and in a closely-divided Congress, that means power. And if these American Conservatives were tough and very principled, their portion would grow and grow over time. Paralysis would hurt the other two parties worse than the upstart.
Another vein of ore to mine is veterans. Despised by Dems and currently being badly used by Republicans (we're sending Marines to courts-martial for killing people in a FIREFIGHT for God's sake!), and you have a potential swelling of ranks on that vector.
Where the thing might come apart aborning is if the new American Conservative Party tried to be both a socially conservative AND economically conservative party. The GOP is economically conservative. That base is covered by them. What is lacking...and what is more numerous...are SOCIAL conservatives and patriots. An American Conservative Party can be practically agnostic on economic issues, or simply cooperate with the GOP on them, but it must above all be a champion of patriotism and SOCIAL conservatism and morals.
So say I, but who am I?
Jim Robinson, now, there's a man with a website that reaches millions of people and has changed recent history. He could put something together swiftly, if he wanted to.
I'm no prize for any movement, but I'd join in a heartbeat.