The poll was taken after Sen. Jay Rockefeller, D-W.Va., announced he would not seek another term for U.S. Senate. Capito had already announced her candidacy for Rockefeller's seat following last November's election.
West Virginia hasn't had a Republican senator since William Chapman Revercomb lost his re-election bid to 40-year-old Democratic upstart Robert C. Byrd in 1958.
Rahall has not committed to entering the race, and several other candidates are also said to be mulling runs in next year's Democratic primary.
While early, the poll shows a significant uphill challenge for any candidate choosing to run.
The poll found Capito holds a 55 percent favorable rating among state voters. No other Democratic challenger had a favorability rating greater than 50 percent.
Among other results, the poll found West Virginians hold a mostly negative view of President Barack Obama. Only 34 percent of state residents approve of Obama's job performance while 59 percent disapprove.
Current Sen. Joe Manchin, D-W.Va., drew a 57 percent favorable rating in the poll. About 36 percent of those surveyed said they had an unfavorable view of the former governor.
Contact writer Jared Hunt at jared.h...@dailymail.com or 304-348-5148.