Selzer national poll: Clinton leads GOP field by 6-13 points

[Mehmentum]

This poll assumes a turnout of 75% likely voters.

Probably too Democratic as well because of this and too many undecided.

Actually, most of the people who didn't chose either candidate are under the category Other/would not vote, which were all voluntary responses.  Only 2 to 5% were undecided.

If you exclude this group the percentages look like:
Clinton: 52% Bush: 45%
Clinton: 52% Romney: 45%
Clinton: 51% Christie: 44%
Clinton: 53% Paul: 44%
Clinton: 55% Cruz: 39%