Four Republican presidential candidates are being invited to a political forum August 20th at the University of Nevada, Reno.

That's two days before a similar event is scheduled for the leading Democrats.

School officials announced today that New Mexico Governor Bill Richardson is the first candidate among the four Democrats to accept the invitation to the August 22nd forum at the Lawlor Events Center.

Democratic Senators Hillary Clinton of New York, Barack Obama of Illinois and ex-Senator John Edwards of North Carolina have not yet responded to invitations that went out this week.

The Brookings Institution, a nonpartisan public policy think tank based in Washington, is cosponsoring the events with the university and ABC News.

School spokeswoman Jan Tors says the institute is in the process of sending out invitations to the four Republicans, former New York Mayor Rudy Giuliani, former Massachusetts Governor Mitt Romney, Arizona Senator John McCain and Texas Congressman Ron Paul.

Republican Fred Thompson has not been invited because he has not formally entered the race. But school officials say that could change.

The sponsors said in announcing the Democratic forum earlier this week they wanted to keep to a limited number of candidates to give them more time to discuss issues.

(Copyright 2007 by The Associated Press. All Rights Reserved.)