This month, after many months of saying that his position on same-sex marriage was "evolving," Obama finally announced he had completed his shift from "I believe that marriage is the union between a man and a woman," as he put it in 2008, to "I think same-sex couples should be able to get married."
The resulting criticism focused not on the honesty of his belief but on his timing — was he just coming out with his support to win contributions from wealthy gay donors? Obama largely escaped the flip-flop charge because, Garin said, "lots of people assumed this was really Obama's position all along."
In contrast, on abortion, Romney had sent mixed signals for most of his political career. He explained his original pro-abortion-rights position on Fox News last year as more a matter of strategy than of principle; when he settled on his original position in Massachusetts, Romney said, he decided that "I'm just going to say I will support the law and preserve the law as it exists."
"Romney is more suspect because he's in the serial offender category," Garin said, noting that on issues such as abortion, gay rights and gun control, the Republican candidate often defends his current positions by saying they aren't that different from his past stances.
That's a tactic that hardly ever works, as evidenced by John Kerry's widely lampooned statement in the 2004 campaign that "I actually did vote for the $87 billion [for the Iraq war] before I voted against it." The flip-flopper tag proved especially sticky in Kerry's case, said longtime Republican advocate Morton Blackwell, because of the public perception of contradictions in Kerry's history as both a veteran and an antiwar activist in the Vietnam era.