(CNN) - Utah Rep. Chris Cannon, consistently ranked among Congress' most conservative Republicans, was defeated Tuesday by a primary challenger who repeatedly argued Cannon was not conservative enough.
Jason Chaffetz, a first-time candidate and former chief of staff to Utah Gov. Jon Huntsman, defeated Cannon by 20 percentage points, 60 percent to 40 percent, with nearly all the precincts reporting.
Chaffetz pledged to be more conservative on illegal immigration policies. Cannon has said he supports a program where undocumented immigrants, who lack a criminal record, could pay a fine to obtain a temporary workers permit. Chaffetz instead advocates a plan to begin gradually deporting all illegal immigrants from the United States. He also supports ending automatic citizenship for children born to illegal immigrants living in the United States.
"We have a mandate to change the way business is done in Washington," Chaffetz told CNN. "We are thrilled. I was outspent by $600,000, I have no paid staff, and no name identification. I said we need to get back to conservative principles and it obviously resonated."
Chaffetz is now essentially guaranteed to win in November. The district, which includes a some of Salt Lake City's suburbs, is overwhelmingly Republican. President Bush won 77 percent of the vote in 2004.
Voter turnout for the primary was extremely low, an ominous sign for the party, Chaffetz said.
"This ought to be a wakeup call the establishment that things are not well. We need to remind people why they are Republicans because they have forgotten, and are not inspired by anybody. "
Cannon is the third member of Congress this year to lose to in a primary this year. In February, Maryland Democratic Rep. Al Wynn and Maryland GOP Rep. Wayne Gilchrest were both defeated in February.