Anybody who has ever campaigned for public office in black churches knows the quickest way to undermine your goodwill among the folks who invited you to worship with them. You never, never, never leave early. Evidently Hillary Clinton’s people haven’t been around this block before.

Clinton shot herself in the foot at what must be one of two black churches in Iowa yesterday.

Hillary Rodham Clinton delivered a campaign sermon Sunday, but didn’t stick around to hear the pastor do his preaching.

“We’re still at church. We’re still going to worship no matter what,” the Rev. Lee Maxey said as the Democratic presidential candidate, her daughter, Chelsea, and their entourage left Corinthian Baptist Church, the media pack close behind.

Clinton stayed for about 20 minutes…

“I think the American people need a president who is their champion. And I’ve been running to be that champion — to get up every single day and do all that I can to make sure I provide the tools that every single American is entitled to receive and make the most out of their own lives,” Clinton said.

And with that, she hurried out. The Rev. James Green took a poke at the just-departed Clinton as he began his sermon.

“When I first got here, I was a little overwhelmed. All the dignitaries came in,” he said. “I thought they were going to stay for service, but they’re still campaigning.”

Ouch. I bet Bill wouldn’t have done that. He would have stayed for refreshments after the service.