Follow this calendar for key dates in the U.S. presidential election, including all primaries, caucuses, debates and conventions. A version optimized for mobile devices can be found on Google Calendar.
Florida Republican primary
Polls in Florida have been especially volatile. Mitt Romney once led by a substantial margin, then Newt Gingrich, and now both are neck-and-neck.
Maine, Nevada caucuses
Colorado, Minnesota caucuses
Missouri, an important state for Republicans, will hold a nonbinding primary to gauge opinion on the candidates, but delegates to the national convention will be decided in the state's caucuses on March 17.
A Republication presidential debate will be hosted by the Arizona Republican Party and broadcast by CNN. The debate was pushed back from its original date in late November, 2011, to coincide with the Arizona primary only six days later.
Arizona, Michigan primaries
A Republican presidential debate will be hosted in Georgia and broadcast by CNN. The debate was organized to coincide with Super Tuesday, happening just five days later, when eleven states hold primaries or caucuses. A Republican nominee may be known by Wednesday, making this a crucial debate for remaining candidates.
Caucuses in Washington
Contests in: Alaska, Georgia, Idaho, Massachusetts, North Dakota, Ohio, Oklahoma, Tennessee, Vermont, Virginia, Wyoming
About one fifth of the delegates will be decided. A winner of the nomination could be known by the next day.
Caucuses in Guam, Kansas, and the Virgin Islands
Caucuses in Alabama, American Samoa, Hawaii, Mississippi
Caucuses in Missouri
Caucuses in Puerto Rico
A Republican presidential debate will be held in Oregon and broadcast through a media partnership of NPR, PBS and The Washington Times. Organizers have boasted the debate comes at a crucial time, just after Super Tuesday. It's also the last scheduled debate for Republicans.
Primaries in District of Columbia, Maryland, Texas, and Wisconsin
Primaries in Connecticut, Delaware, New York, Pennsylvania, and Rhode Island
Primaries in Indiana, North Carolina, and West Virginia
Primaries in Nebraska and Oregon
Primaries in Arkansas and Kentucky
Primaries in California, Montana, New Jersey, New Mexico, and South Dakota
August 27 to 30
Republican National Convention
Republicans will kick off their presidential campaign with the official naming of the candidate in Tampa Bay, Fla.
Democratic National Convention
Democrats will re-nominate President Barack Obama in Charlotte, N.C.
First presidential debate
October marks the beginning of debate season for President Obama, his rival, and their respective running mates. The first in the series takes place at the University of Denver in Colorado.
The Commission on Presidential Debates, a bipartisan group that organizes the events, stated candidates must appear on enough state ballots to have a mathematical chance of winning the presidency and have at least 15 per cent support in the polls. This will almost certainly exclude all third-party candidates.
The first and only vice-presidential debate takes place at Centre College in Danville, Kentucky.
Second presidential debate
The second presidential debate takes place at Hofstra University in Hempstead, New York. This debate will use the familiar "town meeting" format, where presidential candidates are usually provided stools instead of podiums and take questions from a live audience.
Third presidential debate
The third and final presidential debate takes place at Lynn University in Boca Raton, Florida.
Americans vote on who will be the next U.S. president.