With Barack Obama quietly launching a vice presidential selection process and John McCain hosting potential running mates at his Arizona retreat this weekend, political oddsmakers are having a field day.

Various online trading markets have been abuzz for months, attempting to weigh the chances of those considered to be in the running for a vice presidential nod.

Here's a sampling of where the markets stood Thursday:

From Rasmussen Markets (value reflects percentage chance)

On the Democratic side ...

Virginia Sen. Jim Webb: 17.8 percent

New York Sen. Hillary Clinton: 16.9 percent

Former North Carolina Sen. John Edwards: 7.1 percent

Former Vice President Al Gore: 6.9 percent

Ohio Gov. Ted Strickland: 6.7 percent

New Mexico Gov. Bill Richardson: 6.2 percent

Retired Gen. Wesley Clark: 5.4 percent

Former Virginia Gov. Mark Warner: 5 percent

Former Georgia Sen. Sam Nunn: 4.5 percent

Delaware Sen. Joe Biden: 4 percent

Indiana Sen. Evan Bayh: 3.7 percent

Illinois Sen. Barack Obama (if he is not the nominee): 3.2 percent

Former South Dakota Sen. Tom Daschle: 1.1 percent

Connecticut Sen. Chris Dodd: 1 percent

(The "field" category, which represents "any other candidate," was given 33.4 percent odds)

On the Republican side ...

Minnesota Gov. Tim Pawlenty: 18 percent

Former Massachusetts Gov. Mitt Romney: 16.8 percent

Former Arkansas Gov. Mike Huckabee: 11.4 percent

Secretary of State Condoleezza Rice: 6.5 percent

Former New York Mayor Rudy Giuliani: 6.2 percent

Texas Sen. Kay Bailey Hutchison: 5 percent

South Carolina Sen. Lindsey Graham: 3 percent

("Field" category given 46.3 percent odds)

From Intrade Prediction Markets (value reflects percentage chance)

On the Democratic side ...

Webb: 17.8 percent

Clinton: 16.9 percent

Richardson: 8.2 percent

Edwards: 7.1 percent

Gore: 6.9 percent

Clark: 5.4 percent

Strickland: 5.1 percent

Warner: 5 percent

Biden: 4.1 percent

Bayh: 3.7 percent

Nunn: 3.6 percent

Obama: 1.3 percent

("Field" category given 33.1 percent odds)

On the Republican side ...

Pawlenty: 17.5 percent

Romney: 16.7 percent

Huckabee: 11.4 percent

Giuliani: 6.2 percet

Rice: 6 percent

Hutchison: 4 percent

Graham: 2.2 percent

("Field" category given 46.3 percent odds)