WASHINGTON -- Building on Howard Dean's fundraising strategy in 2004, Barack Obama's campaign plans to break the news of his vice presidential choice to people who have signed up to get e-mails and text messages.

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After the news goes out to supporters who have signed up to get the news, along with requests for donations, Obama will make a public announcement. Obama and his newly named running mate will then campaign together Saturday at the place where the Democratic presidential hopeful formally launched his White House bid.

A senior Obama adviser told The Associated Press on condition of anonymity Tuesday that the Illinois senator and his choice for vice president will appear in Springfield, Ill., at the former state Capitol where Abraham Lincoln once served.

The last time Obama appeared there he announced he was running for president.

Obama strategist Anita Dunn sidestepped the question of whether the event would be Obama's first appearance with his vice presidential pick, but suggested the two wouldn't necessarily be related. The campaign's announcement Tuesday said only that Obama would begin the trip to his party's national convention at Saturday's event. The Democratic convention begins Monday in Denver.

"We could pick up the VP. any time," Dunn said.

The campaign has said it will announce the choice via cell phone text message to supporters.

The list of possibilities, meanwhile, is believed to be down to Delaware Sen. Joe Biden, Kansas Gov. Kathleen Sebelius, Indiana Sen. Evan Bayh and Virginia Gov. Tim Kaine, who planned to campaign in his home state Thursday with Obama.

At a town-hall meeting Tuesday night in Raleigh, N.C., Obama repeatedly said "he" when discussing the qualities he sought in a potential running mate, even as campaign officials cautioned reporters not to read too much into his choice of pronouns.

"Let me tell you first what I won't do: I won't hand over my energy policy to my vice president and not know necessarily what he's doing," Obama told the audience. "My vice president ... will be a member of the executive branch. He won't be one of these fourth branches of government where he thinks he's above the law," he said, an apparent reference to Vice President Dick Cheney's handling of the office.

Those thought to be on Obama's short list stayed mum.

Biden coyly told reporters staking out his Delaware home, "I'm not the guy." Sebelius, in an interview with the AP before stumping for Obama in Michigan, professed no inside knowledge of when word would come.

"A week from tomorrow we will all know," she said, referring to the running-mate acceptance speech set for next Wednesday at the convention.

Only Obama, his wife, Michelle, a handful of his most senior advisers and his two-member search committee know for certain who has made the cut.

The running mate decision also looms large for McCain, too.

In hopes of grabbing the post-convention spotlight from Obama, McCain is considering announcing his choice in the few days between the end of the Democratic convention in Denver and the start of the Republican gathering in St. Paul, Minn.

McCain's top contenders are said to include Minnesota Gov. Tim Pawlenty and former Massachusetts Gov. Mitt Romney. Other possible choices are former Pennsylvania Gov. Tom Ridge, an abortion-rights supporter, and Connecticut Sen. Joe Lieberman, the Democratic vice presidential pick in 2000 who now is an independent.

Underscoring how seriously McCain may be considering Ridge or Lieberman, Republican officials say top McCain advisers have been reaching out to big donors and high-profile delegates in key states to gauge the impact of putting an abortion-rights supporter on the GOP ticket.

But conservative radio host Rush Limbaugh warned that the GOP base "will totally turn on McCain" if he picks an abortion-rights running mate and predicted such a move "will ensure his defeat."