The top five prospects, based on reporting, observation and guesswork, in no particular order. Incidentally, I would normally advise my readers to follow my guidance on veepstakes, but for Obama... you'd probably consult Lynn Sweet's lists and give them more weight than mine. (Sweet and I have opposite views on where Sebelius ranks. Honestly, I trust her more than I trust myself!)

And yes, these lists change from week to week. That's part of the fun.

BARACK OBAMA

1. Gov. Kathleen Sebelius (D-KS) -- Obama really likes her; that's very important.
2. The Virginia boys: Kaine and Webb
3. Gov. Ted Strickland (D-OH) -- the Clinton stand in.
4. Gov. Janet Napolitano (D-AZ)
5. Sen. Hillary Clinton -- there's a fine balance between subtle pressure and overt hectoring

Wild card: Sen. Chuck Hagel (R-NE), Sen. Joe Biden (D-DE)

JOHN MCCAIN

1. Gov. Tim Pawlenty (R-MN)
2. Gov. Mitt Romney (R-MA)
3. Mayor Michael Bloomberg (i-NY)
4. Gov. Mark Sanford (R-SC)
5. Sen. John Thune (R-SD)

Wild card: