Why is Mitt Romney having trouble winning over the conservative Republican base? One reason is his lack of political finesse, an air of dorky rich-guy aloofness that reminds some people of John Kerry. More important, however, is his ideological profile. In almost every important way, Romney’s policy platform is more moderate than those of Newt Gingrich and Rick Santorum. Gingrich offers a much more conservative tax plan, along with crowd-pleasing ideas like his plan to sic federal marshals on “radical” liberal judges. Santorum carries a blazing social-conservative torch, championing ideas like a constitutional ban on abortion. Both Gingrich and Santorum talk quite openly about the virtues of bombing Iran. Romney’s temperature runs cooler in all these areas. Not to mention his past record of pro-choice, pro-gay rights positions. As Jon Chait notes today, the GOP establishment is defending Romney but also working hard to push him to the right.