(AP) - Barack Obama readied his announcement by text message Friday of his vice presidential running mate from a list suddenly spiced by a dark horse from Texas.

The prospect of Sen. Hillary Clinton (D-N.Y.) being chosen remained a mystery on a day full of them, although senior aides said the Obama campaign had never requested financial or other records from her.

Three days before the party gathers in Denver to nominate Obama for the fall campaign, several officials said Rep. Chet Edwards, whose district includes President Bush's ranch in Crawford, Texas, had made the roster of potential running mates. Senators Joe Biden, of Delaware, and Evan Bayh, of Indiana, were also in the mix, as were governors Tim Kaine, of Virginia, and Kathleen Sebelius, of Kansas, ? and any unknown others Obama had managed to keep secret despite intense scrutiny.

"It'll be exciting news," Sebelius told reporters in Kansas.

Obama went to the gym for a morning workout before heading to an office in Chicago to polish the convention acceptance speech he will deliver next Thursday night.

Obama told reporters Thursday he's already made his choice, and aides have used the prospect of a text-message announcement to try to attract additional supporters by soliciting their cell phone numbers and e-mail addresses.