Trump looms large over special election primary in deep-red congressional district

Trump endorsed Matt Van Epps, a former commissioner of the Tennessee Department of General Services, in a field that also includes state Reps. Jody Barrett, Gino Bulso and Lee Reeves.

The president's endorsement, even though it came after the finish of early voting in the contest, will likely be the major shaping event of the primary showdown.

The race among the major GOP contenders turned into a test of loyalty to Trump, and with the president's endorsement, Reeves suspended his campaign and backed Van Epps.

"Matt knows the WISDOM and COURAGE required to Defend our Country, Support our Incredible Military/Veterans, and Ensure PEACE THROUGH STRENGTH," Trump said in a statement.

Van Epps, who was also endorsed by Green and Republican Gov. Bill Lee, called Trump's support "an incredible honor."

And on the eve of the primary, the president joined Van Epps for a tele-rally that was co-hosted by the politically influential conservative outside group Club for Growth, which also backed Van Epps.

Van Epps, a lieutenant colonel in the Tennessee Army National Guard and a former Army helicopter pilot, is also backed by prominent House Republican Rep. Jim Jordan of Ohio.

But Barrett, who touts that he is the "most conservative state rep. in Tennessee history," has the backing of the political arm of the House Freedom Caucus, which spent heavily in the primary race.

Four major Democrats are running for their party's nomination. They are state Reps. Vincent Dixie, Aftyn Behn, Bo Mitchell and businessman Darden Copeland.