Find a banner, a cause based upon principles that people will hold up in the air, rally around, follow and fight for, and go from there.
Plenty of causes, but finding principles that enough can agree upon is the harder chore. That's always been the republican challenge, but a much more difficult one today for some reason.
Perhaps it's because they've let everyone else define them instead of doing it themselves and then just went with that. Now, they don't really stand for anything.
America's single member district system necessarily forces us all into two major parties ~ else we'll never get the 50%+1 vote needed to win.
Jefferson was the first to observe this and you should take a look at the vote totals he got!
Then, as like clockwork, the disaffected and disaffiliated began to coalesce into the 'other party' and away we went ~ nip and tuck.
Jefferson's party created its own opposition with internecine battles.
Over time the communities of interest began to form and full bore coalition politics on something other than geographic distribution began.
That's where we've been since about 1850.
If you want strong parties with a single ideological and economic focus like they have in Europe you need to eliminate single member districts! Else, all coalition politics in America will continue to occur prior to elections and separate from the legislative bodies.
Do not imagine the apparent disarray in the Republican ranks is dangerous ~ that's just the way we do it.