Presidential debate live video, Obama vs. Romney: Candidates facing off at University of Denver

-- Co-founder and executive editor of what is now called "PBS NewsHour"; he stepped back from daily anchor duties in May 2011.

-- Has presided over 11 presidential and vice-presidential debates, beginning in 1988.

-- Wrote "Tension City: Inside the Presidential Debates, From Kennedy-Nixon to Obama-McCain."

-- Has compared moderating a presidential debate to "walking on the blade of a very sharp knife."

-- Has been involved in journalism for 53 years, first at newspapers in Dallas, and for 37 years at "NewsHour" in its various forms.

-- Interviewed President Bill Clinton the day the Monica Lewinsky scandal broke and admitted he didn't pick up on Clinton's use of the present tense when he said, "There is no improper relationship."

-- Has won numerous awards, including two Emmys, a George Foster Peabody Award, the National Humanities Medal and the National Press Club's Fourth Estate Award.

-- Has also written 20 novels, two memoirs and three plays.

-- Born in Wichita, Kansas, in 1934.

-- Bachelor's degree in journalism, University of Missouri, 1956.

-- U.S. Marine Corps, 1956-59.

-- Married since 1960; three daughters, six grandchildren.

-- Underwent a heart valve procedure in April 2008 that was deemed "a complete success."