"Congresswoman Capito is not someone we can endorse because her spending record in the House is too liberal. If Republicans in West Virginia want to save their country, they need to find another candidate with the courage say 'no' to more spending and debt," the group's Executive Director Matt Hoskins said. 

Hoskins added that SCF would consider supporting a "strong, viable" challenger recruited by the grassroots in West Virginia.

SCF joins the Club for Growth in criticizing Capito, who announced her bid for Sen. Jay RockefellerJohn (Jay) Davison 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.V.) seat on Monday. Club for Growth President Chris Chocola also bashed the congresswoman for her record on spending, though the group's spokesman, Barney Keller, wouldn't say directly whether the group would consider backing a challenger against Capito in the Republican primary.

But both groups mounted primary challenges in the 2012 election cycle and are expected to do so again in 2014. It's still unclear who would be the preferred candidate of the conservative groups, though sources say Tea Party-backed John Raese, who was defeated by Sen. Joe ManchinJoseph (Joe) ManchinMcConnell to Dems: Don't hold government 'hostage' over DACA Lawmakers see shutdown’s odds rising Senate campaign fundraising reports roll in MORE (D-W.V.) by a 23 percentage point margin this year, could run again.

The congresswoman has long been considered a strong contender to help the GOP pick up a Senate seat in West Virginia, but she's passed on running previously. A source familiar with her thinking said that she feels the time is right for a bid in 2014 because the state has become more Republican over the years.

Rockefeller, 75, could ready for retirement as well, but he has not yet announced his plans.