Jennifer Rubin of Pajamas Media offers "Rallying the Party of 'Not Obama'" (pajamasmedia.com/blog/rallying-the-party-of-not-obama), a laundry list of suggestions for things that the GOP could oppose Obama over; it's a response to those who say the GOP should just concentrate on the positive.

1. The problems the GOP has run much deeper than just not attacking Obama over this or that. The problem is that all their leaders are some combination of corrupt, stupid, or wimpy. It's difficult to find one GOP leader (in politics, the media, or the supposed alternative media) who isn't at least one of those. That extends to their support staff as well. The GOP needs to do a house-cleaning, but not based on ideology so much as competence and integrity. Rubin doesn't go into anything related to that, despite the fact that simply cleaning up their house could be a very strong way to differentiate themselves from the Democrats.
2. The list is, as could be expected, heavy on the "Neo-Con" foreign policy and on pro-business policies. There's little in there that reaches out to the social conservatives she might want in her supposed big tent.
3. She doesn't mention immigration matters at all. Certainly, that's not at the forefront of everyone's mind, but it's certainly odd that she didn't mention it since for a large segment of the GOP base it's a salient issue. And, even after endless mainstream media lies, most people are concerned about it. That issue alone could be used to sour millions of people on the Democrats. Yet, for one reason or another, it's off Rubin's radar (or at least not in her article).
4. The only related issue she mentions is the claim that "In the legal realm, [Republicans] believe in not adhering to identity politics and the endless pursuit of equality of outcomes." In fact, many GOP leaders - and especially consultants - fully buy into those far-left concepts.
5. Some of the things Republicans supposedly oppose are related to things many of them supported during the Bush administration.