Gingrich 37%, Romney 22% Among GOP Voters Nationwide
December 2011
http://www.gallup.com/poll/151355/gingrich-romney-among-gop-voters-nationwide.aspx
Giuliani was running away with things pre-Iowa in late 2007, too. In the +15 to +20 range.
Didn’t win a single caucus or primary, as far as a I can recall.
National numbers mean zilch at this stage, aside from gauging fundraising appeal.