Blackwell, the GOP activist, agreed that faith-driven voters are more likely to demand consistency. In 2004, religious voters were drawn to George W. Bush, the steadfast "decider," over John Kerry, a malleable rationalist, he noted.
"Kerry epitomized the stereotype people have of wishy-washy politicians," said Garin, the Democratic strategist. "With Bush, people said, 'I may not agree with him, but we're in a war and I know he's going to be firm in his conviction to protect America.' "
Barker said his theory explains why John McCain, perceived as a maverick, defeated Romney for the 2008 GOP nomination: "McCain was seen as someone who would stand on principle, but conservative voters didn't trust Romney because they saw him as too willing to change his views."
But there are also elections where the candidates' styles don't match Barker's categories so neatly, and this year is one of them.
Both Obama and Romney are given to arguing that they are following the views of the people, and for Romney, that has caused problems, Barker said: "In Massachusetts, where there aren't many evangelicals, Romney can say he personally opposes abortion but supports keeping it legal because that's what the people want. But in South Carolina, there sure are a lot of evangelicals, and in their view, you're suddenly changing your mind about something they consider murder, and they find that kind of repulsive."
Blackwell said he teaches budding politicians "that if you establish for yourself a set of principles and stick to it, people will trust you." He said the only politician in recent memory who could not be accused of ever changing a position was Jesse Helms, the late Republican senator: North Carolina voters, many of them religious conservatives, "knew Jesse Helms would do exactly what he said, and they could trust him."