The same headline is currently being used online by the Washington Post, the Boston Globe, USA Today, the Guardian, Yahoo News, and many other news sites. The Twitterati were, of course, quick to pick up on the grammar problem (here, here). It's been
to corrected to "…love to hate" by a few outlets already, however (like the Houston Chronicle).
Hard to say how this one slipped by so many editorial eyes. Perhaps an earlier version of the headline had "loves to hate" agreeing with "(the) GOP," such as "2012 hopefuls crowd town GOP loves to hate," and then a last-minute change in word order loused up the agreement.
[Update, 4 pm EST: The AP has now corrected the headline.]