COLEMAN KEEPS THE DOOR UNLOCKED…. It seems former Sen. Norm Coleman (R-Minn.) is having one of those years. In the latest in a series of fiascos, financial data for at least 4,700 Coleman campaign donors was leaked and posted online — including contact information and credit card numbers.

The Republican and his aides are outraged by the “cyber-attack.” The truth is a little more embarrassing.

Former Sen. Norm Coleman’s campaign didn’t do enough to protect donors’ confidential information, and Wednesday that lapse came home to roost as more than 4,700 partial credit card numbers were posted on the Internet.

As data-privacy and security experts criticized the campaign’s handling of a confidential donor database, the Republican and his aides suggested partisan motives — and told donors they should cancel their credit cards. […]

As recently as late January, databases of thousands of Coleman’s donors and assorted contacts sat on a public portion of the campaign’s Web site. They were not password-protected, so a Minneapolis consultant was able to find them by essentially surfing the Web. And the credit card numbers weren’t encrypted — a violation of credit card industry standards, according to several experts.

Kelly McShane, whose job is to secure information in the banking industry, said he learned that the last four digits of his American Express card — and the four-digit security code used to verify the card — were posted online when a reporter e-mailed him.

“I’m in IT security for a bank, and I can tell you that this is so … irresponsible that I can’t believe it,” said McShane, who had donated $100 to the campaign online.

All of this happens to come in the midst of Coleman’s ongoing legal efforts, and his concerted efforts to raise money to pay his bills.

Expect Coleman’s fundraising to dry up quickly this week. Call it a hunch.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.