“Governor Romney has embraced the most strident voices in his party instead of standing up to them,” Obama campaign spokesman Ben LaBolt said in an e-mail. “But Governor Romney’s decision to directly enlist himself in the birther movement should give pause to any rational voter across America.”

The Obama forces followed up with its appeal for money. An e-mail sent by Jim Messina, the campaign’s manager, reprised the birth certificate remark and asks recipients to “take a moment or two to think about that, what he’s actually saying and what it says about Mitt Romney.”

It then asked for donations of $3 or more.