Bob Edgar, 69, president and CEO of Common Cause, died of a heart attack at his home on Tuesday, according to the group.
Edgar was former six-term congressman, elected in 1974, who also headed the National Council of Churches before becoming president of Common Cause in May 2007.
Following his unsuccessful run for the Senate in 1986, he became an active supporter of campaign finance reform. He was on Common Cause's governing board before becoming president.
Earlier this year, Common Cause announced a new plan for combating media consolidation, naming former FCC chairman Michael Copps, a longtime consolidation critic, to head up its Media and Democracy Reform Initiative.
Edgar is survived by Merle, his wife of 48 years; three sons, Andrew, David and Rob, and eight grandchildren.
"I am deeply saddened to learn of the passing of Bob Edgar," said Free Press President Craig Aaron. "He was a great American, a man of faith and a true public servant who fought to make our democracy stronger. He was also one of the kindest people in Washington, always generous with his time and willing to share his experience.... He will be missed, but we will continue working together to carry forward his important work."
"Robert was an inspiring person to work with and always worked for the public's best interest," said Public Knowledge in a statemnt. "His constant fight for a transparent and responsible government was exemplified in his service in the US House of Representatives for 12 years and continued when he became the president and CEO of Common Cause in 2007."