We've been reading for some time about how Democrats hold the lead in polls measuring how the parties will fare in the congressional elections this year. For example, a CNN/USA Today/Gallup Poll reported last week that the Democrats led Republicans among registered voters in the generic congressional survey by 50 percent to 43 percent. However, the Washington Times reports that an analyst at Gallup, David Moore, believes this type of poll overstates Democratic support in congressional races by about 10 percentage points. Moore bases this view on what happened in 1998 and 2002. The bias exists because the polls survey registered voters rather than likely voters. If Moore is correct, the two parties probably are in a statistical dead-heat right now.