But his extremism has just made him more popular with the Republican base voters. Note that 81.8% of teabaggers approve of him, and 75.9% of evangelicals also view him positively. Hell, even 51% of GOP moderates (if there is such a thing) even approve of Cruz.
This should make the Democrats very happy, because the next Republican presidential nominee will most likely be chosen by the teabaggers and evangelicals (especially if they can bring along half of the party's remaining moderates). This means there is a far greater chance the 2016 nominee will be an extremist like Cruz, Paul, Rubio, or Santorum, rather than a more business-oriented moderate like Christie -- and that gives the Democratic candidate (even if it is not Clinton) a much easier road to the White House.