COLUMBIA, S.C. (AP) — Voters of South Carolina's 4th congressional district face a crowded field in Tuesday's primary.

Some 13 Republicans and five Democrats are vying for the seat now held by Rep. Trey Gowdy. He announced his retirement from Congress earlier this year.

Republicans have held the seat anchored by Greenville and Spartanburg for two decades and the 13 candidates represent the spectrum of conservatism from devoutly religious to traditional GOP lawmakers to those with libertarian views.

It makes sense an open seat would attract so many candidates, including those who are at the South Carolina Statehouse, College of Charleston political science professor Gibbs Knotts said.

"It's a logical stepping stone from House or Senate members to U.S. House seats," Knotts said. "This is a very attractive seat."

There are familiar names running: former state Sen. Lee Bright of Spartanburg, who opposes allowing transgender people use the bathroom of their choice; and conservative state Sen. William Timmons of Greenville, who led his competitors as the race entered the final stretch with $670,000 in campaign cash on hand.

Republicans on the ballot along with Bright and Timmons are author Dan Albert; political newcomer Barry Bell; attorney Steven Brown; pastor Mark Burns; small business owner James Epley; state Rep. Dan Hamilton; former Spartanburg Republican Party Chairman Josh Kimbrell; lawyer John Mosser; former nurse and small business owner Shannon Pierce; U.S. Army veteran Justin Sanders; and retired U.S. Army officer Claude Schmid.

With so many candidates in the field, it is doubtful one will get the majority needed to avoid a two-candidate runoff on June 26.

The Democratic candidates running in the 4th District are businessman Brandon Brown; engineer JT Davis; attorney Eric Graben; youth foundation creator Will Morin; and businesswoman Doris Lee Turner.

U.S. Rep Mark Sanford is one of two incumbents facing challengers. The Republican has never lost a race, but faces a well-financed opponent in state Rep. Katie Arrington in the 1st District that includes Charleston and the southern coast. Facing them in the primary is former registered Democrat Dimitri Cherny. On the Democratic ticket, candidates are attorney Joe Cunningham and nonprofit consultant Toby Smith.

Prior to allegations of physical abuse during his first marriage, attorney Archie Parnell seemed like the obvious pick among a field of three Democratic opponents Mark Ali, Sidney Moore and former professional clown Steve Lough in the 5th District. Since the abuse resurfaced, Democratic officials all the way up to the state party chairman have called for Parnell to quit, he has refused.

Parnell nearly beat U.S. Rep. Ralph Norman in the special election last year to fill the seat left vacant when Mick Mulvaney left to run the White House budget office, but Knotts said he may not even get the nomination for a rematch.

"It'll be very difficult to overcome the critics," Knotts said. "Not just the incident itself, but the high profile endorsements that pulled away and will probably dry up resources."

In the 2nd District, Sean Carrigan of Chapin, Phil Black of Lexington and Annabelle Robertson of West Columbia are competing for the Democratic ticket. The winner will face incumbent Republican Joe Wilson in November. Wilson has been a member of Congress since 2001 in the district that includes the western suburbs of Columbia.

In the 3rd District, challengers Mary Geren of Anderson and Hosea Cleveland of Seneca will square off in the Democratic primary. The winner will face incumbent Republican Jeff Duncan, who is seeking a fifth term in November in the district in the northwest part of the state.

In the 6th District, Democratic incumbent James Clyburn, Republican candidate Gerhard Gressmann of Estill, and the Green Party's Bryan Pugh of Orangeburg are running unopposed for their party's nominations in the state's only majority-minority district.

In the 7th District, incumbent Republican Tom Rice faces Republican challenger Larry Guy Hammond of Myrtle Beach. Democratic primary candidates are Bruce Fischer of Longs; Bill Hopkins of Pawleys Island; Mal Hyman of Hartsville; and state Rep. Robert Williams of Darlington for the district that runs from Florence to Myrtle Beach.