Mike Henry has resigned as Hillary Clinton's deputy campaign manager, after campaign manager Patti Solis Doyle left her post Sunday amid a string of defeats to Barack Obama.

Solis Doyle had brought Henry on board, so his departure is not a complete shock.

In an e-mail message to staffers, Henry said he was stepping down to allow new campaign manager Maggie Williams to build her own staff.

"Out of respect for Maggie and her new leadership team I thought it was the best thing to do," Henry wrote. "As someone who has managed campaigns, I share the unique understanding of the challenges that the campaign will face over the next several weeks. Our campaign needs to move quickly to build a new leadership team, support them and their decisions and make the necessary adjustments to achieve the winning outcome for which we have all worked so hard for over a year now."

It was unclear whether Henry was forced out.

Henry, though, was probably best known for having penned a memo last year questioning the wisdom of competing in Iowa.

He called it "our consistently weakest state." The memo was leaked to the media, which embarrassed Clinton as she was beginning to build an organization in Iowa.

Clinton placed third in Iowa, behind Obama and John Edwards, who has since left the race. Her campaign has struggled since then.

Solis Doyle's departure came as Clinton suffered five consecutive defeats to Obama over the weekend.

FOX News' Aaron Bruns and The Associated Press contributed to this report.