NASHVILLE, Tenn. – U.S. Sen. Lamar Alexander has defeated his conservative tea party-backed challenger, state Rep. Joe Carr, in Tennessee’s Republican primary.

The incumbent’s victory on Thursday deals another blow to national tea party momentum after a stunning primary win over Republican Rep. Eric Cantor in Virginia in June.

Carr had garnered high-profile endorsements from tea party-allied figures and portrayed Alexander as being out of step with Tennessee’s increasingly conservative political outlook. But Carr could not make significant gains against the 74-year-old Alexander, a two-term senator and former Tennessee governor.

Unofficial results Thursday showed Alexander with 52.4 per cent of the vote. Carr had 38.4 per cent of the vote with 20 per cent of the precincts reporting.