FACTBOX: Key dates in the U.S. presidential campaign

(Reuters) - Below is a calendar of the remaining U.S. states' 2008 presidential nominating contests as well as other key dates in the campaign for the White House.

In some states the contests are non-binding and separate caucuses or conventions are scheduled to select delegates to the national conventions.

Arizona Sen. John McCain is the presumptive Republican nominee. Illinois Sen. Barack Obama has a nearly insurmountable lead over New York Sen. Hillary Clinton for the Democratic nomination.

MAY

* May 13: Nebraska (Republican), West Virginia

* May 16-18: Hawaii's Republican Party will conduct its state convention; delegates are selected during a week-long process.

* May 20: Kentucky, Oregon. Obama's campaign expects to clinch a majority of pledged delegates after these contests

* May 20: Candidates' April fundraising details to be released

* May 27: Idaho (Republican)

* May 31: The Democratic National Committee's rules and bylaws committee meets to consider seating the delegates from Michigan and Florida, whose elections were disqualified

JUNE

* June 3: Montana, New Mexico (Republican), South Dakota

* Post June 3: Democratic superdelegates -- party leaders and elected officials -- expected to coalesce around a party nominee.

AUGUST

* August 25-28: Democratic National Convention in Denver

SEPTEMBER

* September 1-4: Republican National Convention in Minneapolis-St. Paul, Minnesota

NOVEMBER

* November 4: Election Day

Sources: National Association of Secretaries of State; Reuters News

(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)

(Writing by Jeff Mason and Paul Grant, Washington Editorial Reference Unit),