Every presidential nominee faces a similar problem: in the primaries, you have to appeal to your base voters, tickling the tender parts of the ideological true believers, but in the general, you need to appeal to independents, necessitating a move to the center. The transition from one to the other can be awkward. In the last few days, I've heard a number of Republicans give the same answer when this question is brought up. Isn't their eventual nominee being hurt by the fact that their primaries involve a lot of things like immigrant bashing and coming out against contraception? Nah, they reply, it'll all be OK -- after all, Barack Obama and Hillary Clinton had a hard-fought primary in 2008, and he still won easily in the fall. I suspect we'll be hearing this many times over the next few months, so let me explain why it's completely mistaken.

Obama and Clinton did indeed have a hard-fought primary. It was vigorous, at times even a little ugly. But there's one thing it never was: A contest over who was the most ideologically extreme.

That isn't to say Democrats didn't talk amongst themselves about which candidate was the truer liberal. They did. A lot. I'll confess that I was one of the many who ended up believing, with only the most limited evidence, that Obama would display far more fealty to progressive principles than Clinton would, a belief that turned out to be misplaced. I even once wrote that I thought that on health care, Clinton would see the public option as nothing but a chip to be bargained away, while Obama would fight to keep it (ha!).

But with the exception of a couple of brief moments (like when Clinton criticized Obama for praising Ronald Reagan), that discussion didn't come from the candidates themselves. There were no Clinton ads saying, "Hillary Clinton: The true liberal." Or Obama ads saying, "Barack Obama: Liberal values, a record of liberalism." Their campaign, when it got beyond the day-to-day squabbles, was what then-TAP editor Mark Schmitt called the "theory of change primary" -- not about who was the most liberal in their hearts, but about which method of politics would produce the kind of results they agreed on.

There may be almost no difference between what Mitt Romney and Rick Santorum actually propose to do once each becomes president. But they and the other candidates have spent the last few months saying, in full view of the entire electorate, "I'm the most conservative!" "No, I'm the most conservative!" You got ads like this one, in which Santorum attacks Romney for his prior liberal positions, and ends with the tag line, "Rick Santorum: A trusted conservative." You've got this Ron Paul ad saying Santorum's a "fake conservative." You've got Mitt Romney feeling so much pressure that he has to proclaim that as governor he was "severely conservative." All that produces headlines like this one: "Romney, Santorum battle over who's more conservative."

So the nominee, most likely Romney, will have to distance himself from all that once the fall comes. And quite conveniently for Barack Obama, that will necessitate some ideological squirreliness that will reinforce exactly the critique the Obama campaign will be making of his character.

It’s always useful to have the proper context when evaluating the popularity of a presidential candidate. Otherwise, it’s hard to know if you’re looking at a deviation, or the usual pattern. Mitt Romney’s high unfavorables are unusual, for example, but the real question is how unusual? To that end, Talking Points Memo has a chart comparing the favorability of presidential candidates over the last decade:

Mitt Romney is set to speak before the Detroit Economic Club later this morning to expound upon his recently unveiled tax policy. Befitting the importance his campaign has placed on the event and his self-perceived status as the frontrunner, Romney will address the group at Ford Field, home to the Detroit Lions, a stadium which seats 65,000. The only problem for the Romney campaign is that there isn't a throng of thousands interested in turning out during lunch for a lesson on fiscal policy. As the Detroit Free Press reported, the stage and audience will be situated to make the 1,200 attendees look as if it's as packed as any NFL game:

Yet another poll shows Rick Santorum with a lead among Republican women; according the latest survey from ABC News and The Washington Post, 57 percent of Republican women have a favorable view of the former Pennsylvania senator, compared to the 61 percent who have a favorable view of Mitt Romney. What’s more, as The Post notes, Romney has higher negative ratings among GOP women than Santorum does—28 percent to 18 percent.

It only took about an hour into the 20th Republican debate Wednesday for the candidates to find something they could agree on. After sparring over the fine details of earmarks, Mitt Romney, Ron Paul, Newt Gingrich, and Rick Santorum agreed that it’s all right for women to serve in the military but birth control, well, that’s a slippery slope that leads to the breakdown of society.

Supporting the right of women to serve in the armed forces, itself a completely irrelevant debate considering 167,000 women are active-duty military, while trying to limit access to birth control, betrayed a profound ignorance on the way that women lead their lives.

Apparently, Rick Santorum is displeased that he's being forced to talk about stuff like contraception, and Satan's war on America, when other candidates aren't getting the same kind of questions. One of his aides made the complaint to conservative journalist Byron York:

But specifically religious questioning of Romney is as rare as specific Romney statements about Mormon beliefs. Given the current grilling of Santorum, that is a source of growing frustration to Santorum's advisers. "Why is Mormonism off limits?" asks one. "I'm not saying it's a seminal issue in the campaign, but we're having to spend days answering questions about Rick's faith, which he has been open about. Romney will turn on a dime when you talk about religion. We're getting asked about specific tenets of Rick's faith, and when Romney says, 'I want to focus on the economy,' they say, OK, we'll focus on the economy."

In one way, Santorum's people have a point. Reporters haven't asked Romney lots of questions about Mormonism, for a few reasons. First, Romney does almost no interviews or press conferences, so reporters seldom get the chance to ask him about anything. Second, as the Santorum aide says, Romney will quickly deflect any question about Mormonism to a more general point about the importance of faith, Obama's "war on religion," blah blah blah. And finally, I suspect reporters are a little nervous about seeming intolerant. If you start asking Romney questions about the more colorful aspects of Mormon theology, you might sound like your being intolerant of a minority religion and implying that Romney's faith could be disqualifying. On the other hand, Santorum is quite happy to talk about what he thinks God wants and what he thinks God hates, speaking in much more concrete terms about religion than Romney ever does...

Tammy Duckworth, a Democrat who is making her second run for Congress, lost both her legs when her Black Hawk helicopter was shot down by a rocket-propelled grenade in 2004. Duckworth first ran for Congress in 2006, but lost to Republican Peter Roskam. Now, the EMILY’s List candidate looks poised to win her primary in the Illinois 8th, and the seat in November. A 48-year-old Iraq War veteran, Duckworth has based much of her platform on veterans’ advocacy—a cause that was sparked by her first-hand experience recovering at Walter Reed Army Medical Center.