Indiana Gov. Mitch Daniels told supporters in an email early Sunday that he will not run for president in 2012, a decision he said ultimately came down to his family’s reticence about a campaign.

The announcement by the former Office of Management and Budget director and favorite of much of the Republican establishment will again roil the unsettled GOP field—and likely intensify efforts to convince another major candidate to join the race, such as former Florida Gov. Jeb Bush or New Jersey Gov. Chris Christie.

The Daniels email, obtained by POLITICO, went out from Indiana GOP chief Eric Holcomb, a key Daniels adviser, soon after midnight, with the word “Urgent” in the subject line.

“The following is from Governor Mitch Daniels….” the email began.

“I hope this reaches you before the public news does,” Daniels wrote. “If so, please respect my confidence for the short time until I can make it known to all.”

“The counsel and encouragement I received from important citizens like you caused me to think very deeply about becoming a national candidate. In the end, I was able to resolve every competing consideration but one, but that, the interests and wishes of my family, is the most important consideration of all. If I have disappointed you, I will always be sorry.”

Daniels, who had deep fundraising ties from his time in the Bush administration and his own years in Washington, went on: “If you feel that this was a non-courageous or unpatriotic decision, I understand and will not attempt to persuade you otherwise. I only hope that you will accept my sincerity in the judgment I reached,” he wrote.

“Many thanks for your help and input during this period of reflection. Please stay in touch if you see ways in which an obscure Midwestern governor might make a constructive contribution to the rebuilding of our economy and our Republic.”

The email, which went to a list of supporters but not the Indiana GOP’s broader email list, was unusual —pols who bow out of campaigns rarely choose to announce it just after midnight on a Saturday.

But it was a reminder that Daniels has always tended to march to the beat of his own political drum, keep his own counsel and do things his own way.

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