West Virginia Secretary of State Natalie Tennant (D) will launch a bid for Senate next week, sources confirm, setting up Democrats with their best remaining shot at retaining Sen. Jay RockefellerJay RockefellerOvernight Tech: Trump nominates Dem to FCC | Facebook pulls suspected baseball gunman's pages | Uber board member resigns after sexist comment Trump nominates former FCC Dem for another term Obama to preserve torture report in presidential papers MORE's (D-W.Va.) seat.

Tennant will reportedly kick off her campaign next Tuesday, and then is expected to tour cities around the state.

She faces a difficult battle against top GOP recruit Rep. Shelley Moore CapitoShelley Wellons Moore CapitoSenate women: Rules on harassment must change Congress, here's a CO2-smart tax fix to protect, create jobs Women, Dems leading sexual harassment discussion in Congress: analysis MORE (W.Va.), who is currently considered the frontrunner in the red-leaning state. The Senate seat is open in 2014 with the retirement of Sen. Jay Rockefeller (D). 

Though West Virginia hasn't sent a Republican to the Senate since 1956, Obama lost the state by about 25 percentage points in 2012, and Republicans see the seat as a prime pickup opportunity in their quest to retake the Senate.

Brook Hougesen, spokeswoman for the National Republican Senatorial Committee, immediately drew comparisons between Tennant and Senate Majority Leader Harry ReidHarry ReidBill O'Reilly: Politics helped kill Kate Steinle, Zarate just pulled the trigger Tax reform is nightmare Déjà vu for Puerto Rico Ex-Obama and Reid staffers: McConnell would pretend to be busy to avoid meeting with Obama MORE in a statement on her entrance into the race.

“Natalie Tennant is a cookie-cutter liberal more in the mold of Harry Reid (D-Nev.) than Joe ManchinJoseph (Joe) ManchinTrump rips Dems a day ahead of key White House meeting Senate panel moves forward with bill to roll back Dodd-Frank Wealthy outsiders threaten to shake up GOP Senate primaries MORE (D-W.Va.) on issues like coal, energy, the EPA, ObamaCare, abortion and protecting the 2nd Amendment," she said.

She also suggested that Tennant is strategically useful for Republicans, because she could draw resources and energy from other candidates.

Strategically, Tennant is great for Republicans in that she's enough of a mirage to keep National Democrats and donors walking through the desert without offering the ability to ever drink," Hougesen said.

Republicans need to net six seats to regain the majority and have been counting on West Virginia, along with two other open seats where Democrats have been unable to front a strong candidate, as probable wins.

Tennant's entry into the race, however, gives Democrats a strong recruit. She was previously a businesswoman and broadcast journalist before winning the 2008 race for secretary of State with more than 60 percent of the vote.

She also ran unsuccessfully for the Democratic nomination in West Virginia's 2011 gubernatorial special election.

--This piece was updated at 4 p.m. to reflect comment from the NRSC.