Freshman Rep. David Davis (Tenn.) was upset Thursday in a Volunteer State GOP primary race that political observers said only underscores the strength of the anti-Washington, D.C., sentiment across the nation heading into the November elections.

Johnson City Mayor Phil Roe, who finished in fourth place in the 2006 GOP primary that Davis won, finished ahead of the Congressman in Thursday’s balloting by about 500 votes — or less than 1 percent.

Roe is now expected to cruise to an easy victory in November’s general election in the strongly Republican 1st district.

Roe ran a grass-roots campaign that, for the most part, flew under the radar of national observers. Roe is an ob-gyn and Army veteran who has painted himself as a political outsider. In the 2006 campaign, he toured the 12-county district on bicycle.

Davis won the 13-way 2006 primary with just 22 percent of the vote, but he had established a very low profile on Capitol Hill since coming to Congress.

Democratic strategists happily pointed out that Roe made Davis’ connections to oil companies a key component of his attacks on the freshman Congressman, mirroring the strategy that Democrats are hoping to employ against Republicans nationwide this fall. In one campaign ad, Roe charged that Davis was in the pocket of Big Oil and out of touch with his eastern Tennessee distinct.

Davis is the fourth incumbent to be defeated in a primary so far this cycle. His loss last week follows those of GOP Reps. Chris Cannon (Utah) and Wayne Gilchrest (Md.) and Democrat Albert Wynn (Md.).