"It's a huge blow to President Obama, and a big boost to the Republicans, particularly to the Tea Party grass roots, " says Dean Clancy, a health specialist at Freedomworks, a conservative campaign group.

BBC: President Obama faces tough choices on healthcare

Members of the Tea Party Express, a leading arm of the grass-roots movement, have traversed the state by bus in support of Cruz.

CNN: Texas GOP Senate primary heads to runoff

Politically inclined grass-roots activism on both the right and left is alive and well on Meetup in the thriving number of tea party and Occupy Wall Street groups using the site.

CNN: From Howard Dean to the tea party: The power of Meetup.com