Democrats could only dream of having it that easy. There's simply no coalition for a Tea Party Presidential candidate unless that person is faking it to make it out of the GOP primary. Democratic candidates don't need Republican votes to win the Residency anymore and increasingly won't need Independents, either. Not when Democrats are outnumbering Republicans in Presidential elections by 6 points or more and have been outnumbering the GOP in party identification polls pretty consistently since after 2004.
Republican candidates need their entire base to vote for them and lots of Independents just to remain competitive. We saw that with John McCain and Mitt Romney, who have the third and second most votes of any Republican in history, respectively, and still lost. (George W. Bush holds the record with 62 million in 2004, which wouldn't have been enough to win either 2008 or 2012.)
But the Tea Party (aside from a few common sense issues like civil liberties, yet apparently not civil rights) is so far to the right that it often can't win a majority of the Republican base. How could someone like Ted Cruz win in 2016 under these conditions?
The answer is that neither he nor any other true members of the Tea Party can do it. The demographic advantage for Democrats has become so pressing in presidential elections that the Tea Party would have to equal both the GOP and Democratic Party in size, and then find votes from one of those two camps to push it over the top. Yet for every vote the Tea Party gains, its natural supply of converts loses one: the GOP.
The stronger the Tea Party gets (assuming it didn't peak in 2010, which it probably did), the weaker the conventional Republican Party will become, the stronger Democrats will get.
This is how things are today:
But most Independents are partisans that wear their party identification like a new purse or pair of expensive shoes. So when "leaners" are pushed into one or the other, you get:
To create a Tea Party, you'd get something like this (inferred):
Tea Party: 18%
The right would be well on its way to emulating British politics, but nearly permanently depriving itself of executive power until either the entire GOP moves far enough to the right that it is indistinguishable from the Tea Party (at that point, moderate Republicans would become moderate Democrats and Independents would become moderate Democrats, pushing Dems well over 50%), or the two factions become permanently fractured.
There simply aren't enough ultra conservatives in America to ever be a force unto itself.
* * *
This story about Cruz not getting along with the club in Washington is typical of the social dysfunction in government. I don't have a problem with a Senate rookie not playing by the gentleman's club rules. That's funny. But pretending that being an raging ass makes you cool and a rising star is wrong. People like this are more like meteorites that burn up in the atmosphere. They are temporary freak shows. Palin, Ted Cruz, same deal. Having no regard for the club rules is fine. Having no regard for anything just makes you a douche. And there's nothing The Club hates more than someone they can't invite to their little Georgetown cocktail parties.