And your history would be wrong. Both of the current parties, Democrats and Whigs, were third parties at some point.
When the Whigs found themselves on the wrong side of the slavery argument, they were destroyed. If the GOP is on the wrong side of the abortion argument, they’ll be destroyed too.
We need a party that just as they were opposed to slavery, is apoosed to abortion. If that party is not the GOP, they will fade and die away. There’s already a pro abortion party, it’s called the Democrats. We don’t need another.