In NH, registered voters excluded by CNN's LV screen favor Shaheen 66% to 24%. 51% of these registered voters say "their mind is made up", yet they're excluded.
CNN/ORC has a likely voter screen that's ~7% worse for Democrats compared to their numbers for registered voters. They've published four polls in US Senate races (that I've seen) from Arkansas, Iowa, Kentucky and New Hampshire (PDFs).
Registered voters excluded by the LV screen favored the Democrat by wide margins: an estimated 27 points in Arkansas, 22 points in Iowa, 8 points in Kentucky, and 42 points in New Hampshire. That's how an LV screen moves things 7%.
Credit to CNN for publishing numbers for both registered and likely voters, unlike most pollsters. I'm not here to argue against LV screens in general, but greater disclosure by pollsters would be nice.