In a March 2011 photo, West Virginia Secretary of State Natalie Tennant is seen in her office in XXX , W.V. Tennant is one of six Democrats running for governor in the May 14 primary. This year's special gubernatorial election is to fill the remaining term of former Gov. Joe Manchin, who was elected to the U.S. Senate last year following the death of Sen. Robert C. Byrd. (Brittany Erskine/ Associated Press) West Virginia Secretary of State  Natalie Tennant (D), shown in March 2011.(Brittany Erskine/ Associated Press)

West Virginia Secretary of State Natalie Tennant (D) is expected to announce next week that she will run for Senate, according to three people with knowledge of her plans.

Tennant is perhaps the last remaining big-name recruit for Democrats, who have struggled to find a standard-bearer for the seat held by retiring Sen. Jay Rockefeller (D-W.Va.).

She is expected to make her campaign official Tuesday, followed by stops in a few cities across the state.

Rep. Shelley Moore Capito (R-W.Va.) is the odds-on favorite on the Republican side.

Tennant, 45, was a businesswoman and TV anchor before being elected as Secretary of State in 2008. Her biography also includes a stint as the West Virginia University's Mountaineer mascot.

She ran for governor in 2011, finishing third in a crowded primary. She was reelected as secretary of state last year, taking 62 percent of the vote.

West Virginia is one of three red states where Democrats are still seeking to replace a retiring Democratic incumbent on the ballot. National Democrats are still recruiting to find replacements for retiring Sens. Max Baucus (D-Mont.) and Tim Johnson (D-S.D.) after having lost out on big-name recruits.

Brad Dayspring, a spokesman for the National Republican Senatorial Committee, said Tennant will give Democrats false hope in a red state.

"Strategically, Tennant is great for Republicans in that she's enough of a mirage to keep National Democrats and donors walking through the desert," Dayspring said, adding that Tennant is "far too liberal" for a Senate race.

Updated at 2:22 p.m. Ed O'Keefe contributed to this report.