Take the 2008 and 2010 general elections as good examples. In 2008, the actual West Virginia voting electorate was 55 percent Democratic to 33 percent Republican, representing 1.69 Democratic voters for each Republican, and yet Sen. John McCain, R-Ariz., beat Obama by a full 13 points 56 percent to 43 percent. In 2010, the state's voting electorate was 56 percent Democratic to 34 percent Republican, representing 1.63 Democrats per Republican, yet in this case, now-Sen. Joe Manchin defeated his GOP opponent by 10 points, 53 percent to 43 percent.
It's apparent that raw party registration data in a state like West Virginia is of limited use in determining how actual votes are being cast, compared to a state like Nevada, in which the final results in this month's House special somewhat mirrored the turnout by party. Nevada also has more new voters, who tend to vote more with the party with which they register.
None of this should be interpreted as meaning Tomblin is somehow in trouble headed into Tuesday. Polling indicates Tomblin still heads into Tuesday as the favorite, and businessman Bill Maloney will need to attract enough crossover voters and boost base GOP turnout to have a chance, which is no small task.