The AP reports on Barack Obama's changed opinions on issues over time. Chief among them:

• The death penalty

  In 1996, when he was running for a seat in the Illinois Senate, Obama's campaign filled out a questionnaire flatly stating that he did not support capital punishment. By 2004, his position was that he supported the death penalty "in theory" but felt the system was so flawed that a national moratorium on executions was required.

  Today, he doesn't talk about a moratorium and says the death penalty is appropriate for "some crimes — mass murder, the rape and murder of a child — so heinous that the community is justified in expressing the full measure of its outrage."

• The Patriot Act

  When he ran for the Senate, Obama called the act a "shoddy and dangerous law" that should be replaced. After he took office, the Senate considered an update that Obama criticized as only a modest improvement and one that was inferior to other alternatives. Still, Obama ended up voting for that renewal and update of the Patriot Act.

The article says Democrats are unlikely to attack him on his changing positions for fear of seeming negative, but Republicans may not show such restraint. Another person interviewed in the article thinks Republicans will use a different argument:

"If Obama is the Democratic candidate, I don't think the Republicans will be attacking him on a particular issue," said Dianne Bystrom, director of the Center for Women and Politics at Iowa State University. "They'd be attacking him on his experience."

Update: Obama is now criticizing John Edwards' record. I thought negativity didn't play in Iowa....