I hate to be pessimistic but the only party we have is GOP. We are weak as a Conservative base to start another. It makes me sick.
For those of us who live in solid blue states it might make more sense to try and split the Dem vote then add to the meager GOP vote.
I've advocated this in the past, but I think it mostly falls on deaf ears:
1. Not enough people care enough to vote strategically
2. Some people think it is immoral to vote strategically
3. Some people think it is immoral to vote for particular parties such as the Green Party because they are pro-aborts, etc.
4. Some people are just dyed-in-the-wool Pubbies. They're almost as rabid (and unthinking) as sports fans.
5. Some people are afraid it will backfire
I re-registered as Dem since I live in Cali and was able to vote against the Hildebeast twice: once by voting for Bernie and once by voting for Trump.
So regardless of the fecklessness of my vote, it did bring me great personal satisfaction.