One of the key strategic decisions facing the Obama campaign now that Mitt Romney has completely nailed down the GOP nomination is whether to go after him as too conservative for the country, or as a slippery flip-flopper who might do anything. The former is a tried-and-true tactic that exploits the unusual ideological militancy afflicting the GOP this year and takes advantage of Romney’s many efforts to placate “true conservatives.” The latter approach has the advantage of reinforcing conservative doubts about Romney–which are still fresh in everyone’s memory, of course–and also casting doubt on Mitt’s character, like the GOP’s “flip-flop” campaign against John Kerry in 2004.
The first sign from Team Obama squarely takes the “he’s too conservative” tack:

From the Obama campaign, CNN reports:
“Expect us to keep holding Romney accountable for the positions he committed to during the primary. There will be no Etch A Sketch opportunities this year,” Obama campaign press secretary Ben LaBolt said.
This is, of course, just a web video, and distribution of it can be targeted to people most likely to be offended by Romney’s pander-fest to the Right (including potential Obama-Biden donors). It by no means precludes different attack lines later, including the flip-flop charge. But it’s an interesting sign of the Obama campaign’s current thinking.