Sen. Roger Wicker and 1st District Rep. Alan Nunnelee, both Republicans from Tupelo, are seeking their first re-elections in their current offices. Friday was the qualifying deadline for the primary.
"If you're going to try to unseat an incumbent, the best time is in their first term," said Dr. Marty Wiseman, chief of the Stennis Institute of Government at Mississippi State University. "It's usually when they're more politically vulnerable."
But Wiseman notes it's unusual, to date, that Mississippi contests occur in the Republican primary. He speculates that's because direct opposition has diminished from the once-powerful Democrats.
Wicker picked up two primary challengers - E. Allen Hathcock of Stewart and Robert Maloney of Madison. Wicker won a special election in 2008 and seeks his first full six-year term.
Democrats Albert N. Gore Jr. of Starkville, Dr. Roger Weiner of Clarksdale and Will Oatis of Silver Creek will compete to see who meets the GOP winner on the November ballot.
Five men want to be north Mississippi's next U.S. House member. Nunnelee won the seat two years ago when he defeated Democratic incumbent Travis Childers of Booneville.
His March 13 GOP primary opponents are Southaven businessman Robert Estes and Eupora attorney Henry Ross. Nunnelee beat Ross for the 2010 GOP nomination.
Nunnelee said he's not surprised by the competition: "That's what the American system is all about."
Brad Morris, an Oxford attorney and Childers' former chief of staff, seeks to regain the House seat for the Democrats. He'll sail into the Nov. 6 general election after withdrawal by fellow Democrat Mark DuVall of Mantachie.
Rounding out the field is Danny Bedwell, a Columbus businessman and state chairman of the Mississippi Libertarian Party.