No doubt some of the senators are hedging because they realize that it will take 67 Senate votes (while President Obama is still in office) to overcome a veto of any repeal measure. But the answer to that is to be straightforward with the American people about the existing institutional obstacles to repeal, not simply to concede the struggle.
On the other hand, it's also right -- as I argued here -- to advocate "repeal and replace." To insist on nothing but repeal opens Republicans to charges that they are content with the status quo -- which isn't the case (although it's better than ObamaCare!). In the long run, a negative approach (against ObamaCare, without any positive reform of our own) can't win and keep the confidence of the American people.
If the party is truly serious about leading and offering a true alternative to Democrats, it needs to be clear on how its members would address the existing issues in health care where Americans do want reform. It's a great opportunity to explain the difference in the two parties' approaches: The Democrats want to put the government in control, while the Republicans want American families to control their own healthcare decisions.
But make no mistake: ObamaCare must be repealed before it can be replaced with something less hostile to freedom, free enterprise, and regular Americans.