| January 3, 2012 | Iowa (caucus) |
| January 10, 2012 | New Hampshire (primary) |
| January 21, 2012 | South Carolina (primary) |
| January 31, 2012 | Florida (primary) |
| February 4, 2012 | Nevada (caucus) |
| February 4–11, 2012 | Maine (caucus) |
| February 7, 2012 | Colorado (caucus) Minnesota (caucus) Missouri (primary) – *See note below on Missouri |
| February 28, 2012 | Arizona (primary) Michigan (primary) |
| March 3, 2012 | Washington (caucus) |
| March 6, 2012 (Super Tuesday) | Alaska (caucus) Georgia (primary) Idaho (caucus) Massachusetts (primary) North Dakota (caucus) Ohio (primary) Oklahoma (primary) Tennessee (primary) Vermont (primary) Virginia (primary) |
| March 6-10, 2012 | Wyoming (caucus) |
| March 10, 2012 | Kansas (caucus) U.S. Virgin Islands (caucus) |
| March 13, 2012 | Alabama (primary) Hawaii (caucus) Mississippi (primary) |
| March 17, 2012 | Missouri (GOP caucus) – *See note below on Missouri |
| March 20, 2012 | Illinois (primary) |
| March 24, 2012 | Louisiana (primary) |
| April 3, 2012 | District of Columbia (primary) Maryland (primary) Wisconsin (primary) Texas (primary) |
| April 24, 2012 | Connecticut (primary) Delaware (primary) New York (primary) Pennsylvania (primary) Rhode Island (primary) |
| May 8, 2012 | Indiana (primary) North Carolina (primary) West Virginia (primary) |
| May 15, 2012 | Nebraska (primary) Oregon (primary) |
| May 22, 2012 | Arkansas (primary) Kentucky (primary) |
| June 5, 2012 | California (primary) Montana (primary) New Jersey (primary) New Mexico (primary) South Dakota (primary) |
| June 26, 2012 | Utah (primary) |
