JACKSON (AP) — In an unusual year with two U.S. Senate seats up for grabs in Mississippi, Republican Thad Cochran should be able to run a low-budget, low-stress campaign for re-election.

But the other race is set to become an expensive and hard-fought contest.

Three high-profile candidates qualified to run Friday for Mississippi’s U.S. Senate seat that is being filled by a special election. Republican Roger Wicker wants to retain the seat he got by appointment on Dec. 31 after the resignation of the GOP’s Trent Lott. The two Democrats who signed up to run are former Gov. Ronnie Musgrove and former U.S. Rep. Ronnie Shows.

Cochran, first elected to the Senate in 1978, is unopposed for his party’s nomination in his race. The two Democrats who signed up for their party’s Senate primary — former state Rep. Erik Fleming of Clinton and perennial candidate Shawn O’Hara — have lost statewide elections after failing to raise enough cash to run effective campaigns.

Friday was candidates’ qualifying deadline for the Senate seats and for four Mississippi U.S. House seats. Party primaries are March 11 and the general election is Nov. 4.

Two of Mississippi’s U.S. House seats are wide open.

Republican Chip Pickering announced several months ago that he would not seek re-election in the 3rd District, which stretches from Natchez to the Jackson suburbs to Starkville. Pickering was first elected in 1996.

Wicker recently stepped down from the congressional post in north Mississippi’s 1st District because Gov. Haley Barbour appointed him to temporarily fill the Senate seat that Lott left. Wicker was first elected to the House in 1994.

The 1st District Democratic candidates are Prentiss County Chancery Clerk Travis W. Childers of Booneville, Marshall W. Coleman of Calhoun City, state Rep. Steve Holland of Plantersville, James K. ‘‘Ken’’ Hurt of Verona and Brian Neely of Tupelo.

The 1st District Republican candidates are Mayor Greg Davis of Southaven, former Mayor Glenn McCullough Jr. of Tupelo and Randy Russell of Oxford.

Independent Wally Pang and Green Party candidate John M. Wages Jr. also filed to run in the 1st District. Their cities were unavailable. They will not have primaries.

The 3rd District Democratic candidates are Randy Eads of Starkville and Joel L. Gill of Pickens.

The 3rd District Republican candidates are James Broadwater of Flowood, Hardy Caraway of Quitman, Gregg Harper of Pearl, Gregory Hatcher of Meridian, David Landrum of Madison, Bill Marcy of Meridian, former state Sen. Charlie Ross of Brandon and John Rounsaville of Madison.