According to a White House aide, the president found out about the switch at 10:25 AM while in the Oval Office receiving his Economic Daily Briefing.
The White House released a photo Tuesday of the president on the phone with Specter
The president was handed a note, the aide said, that read: "Specter is announcing he is changing parties."
Seven minutes later, President Obama reached Specter to tell him, according to the aide, "You have my full support" and that we are "thrilled to have you."
From Huffington Post. Learn more @ http://www.huffingtonpost.com/2009/04/28/obama-to-specter-we-are-t_n_192309.html