Question: When did the Democratic senator in the United States vice-presidential debate of 1976 run for presidential election?

Context paragraphs:
United States vice-presidential debate, 1992: The 1992 vice-presidential debate was part of the 1992 presidential election.  The participants were Democratic nominee, Bill Clinton's running mate, U.S. Senator Al Gore from Tennessee; Ross Perot's running mate, retired Vice Admiral James Stockdale; and Republican candidate, incumbent Vice President Dan Quayle.  It was held on Tuesday, October 13, 1992.

Senator, you're no Jack Kennedy: "Senator, you're no Jack Kennedy" was a remark made during the 1988 United States vice-presidential debate by Democratic vice-presidential candidate Senator Lloyd Bentsen to Republican vice-presidential candidate Senator Dan Quayle in response to Quayle comparing himself to John F. Kennedy, the 35th President of the United States.  Since then, the words "You're no Jack Kennedy", or some variation on Bentsen's remark, have become a part of the political lexicon as a way to deflate politicians or other individuals perceived as thinking too highly of themselves.

United States presidential election, 1996: The United States presidential election of 1996 was the 53rd quadrennial presidential election.  It was held on Tuesday, November 5, 1996.  The Democratic national ticket was led by incumbent President Bill Clinton, and his running mate, incumbent Vice President Al Gore.  The Republican nominee for President was Bob Dole, the former Republican Leader of the United States Senate and long-time Senator from Kansas who was previously the vice-presidential running mate of President Gerald Ford in 1976, following Vice President Nelson Rockefeller's retirement from politics that year.  Dole's running mate for Vice President was Jack Kemp, a former NFL football player and the Housing Secretary under George H. W. Bush.  Businessman Ross Perot ran as candidate for the Reform Party with economist Pat Choate as his running mate; he received less media attention and was excluded from the presidential debates and, while still obtaining substantial results for a third-party candidate, by U.S. standards, did not renew his success of the 1992 election.  Turnout was registered at 49.0%, the lowest for a presidential election since 1924.

Walter Mondale: Walter Frederick "Fritz" Mondale (born January 5, 1928) is an American politician, diplomat and lawyer who served as the 42nd Vice President of the United States from 1977 to 1981, and as a United States Senator from Minnesota (1964–76).  He was the Democratic Party's presidential nominee in the United States presidential election of 1984, but lost to Ronald Reagan in a landslide.  Reagan won 49 states while Mondale carried his home state of Minnesota and Washington, D.C.

United States vice-presidential debate, 2008: The 2008 United States vice-presidential debate took place on October 2, 2008, between U.S. vice-presidential candidates Sarah Palin, the Governor of Alaska, and Joe Biden, the senior Senator for Delaware, at Washington University in St. Louis, and was moderated by Public Broadcasting Service journalist Gwen Ifill.  It was the first such debate to feature a female candidate since the 1984 vice presidential debate.  The debate was watched by about 70 million viewers according to Nielsen Media Research, making it the most-watched vice-presidential debate in history.  It was only the second presidential or vice-presidential debate to surpass 70 million viewers, the first being the 1980 presidential debate between Governor Ronald Reagan and President Jimmy Carter, which drew nearly 81 million viewers.

Say It Ain't So, Joe (opera): Say It Ain't So, Joe is a chamber opera in two acts by Curtis K. Hughes inspired by text drawn from the public record of the 2008 United States vice-presidential debate where vice presidential candidate Joe Biden is addressed by Sarah Palin in a similar manner as the famous quote referring to Shoeless Joe Jackson.  Commissioned and produced by Guerilla Opera, "Say It Ain't So, Joe" premiered in Boston on September 19, 2009 at the Boston Conservatory Zack Box Theater.

United States vice-presidential debate, 1976: This debate featured U.S. Senator Walter Mondale from Minnesota, the Democratic vice presidential nominee, and U.S. Senator Bob Dole from Kansas, the Republican vice presidential nominee.

Thomas C. O'Brien: Thomas C. O'Brien (June 19, 1887-?)  was an American labor lawyer from Boston.  He was the United States vice-presidential nominee for the Union Party in the 1936 United States presidential election

United States presidential debates, 2016: The 2016 United States presidential election debates were a series of debates held for the 2016 U.S. presidential general election.  The Commission on Presidential Debates (CPD), a bipartisan organization formed in 1987, organized three debates among the major presidential candidates.  The first presidential debate for the 2016 election took place on September 26, 2016, and set the record as the most-watched debate in American history, with 84 million viewers.  The only vice-presidential debate was held on October 4.  The second presidential debate took place on October 9, and the final debate took place on October 19.  All CPD debates occurred from approximately 9 p.m. to 10:30 p.m. EDT (6 p.m. to 7:30 p.m. PDT).

United States presidential election, 1972: The United States presidential election of 1972, the 47th quadrennial presidential election was held on Tuesday, November 7, 1972.  The Democratic Party’s nomination was eventually won by Senator George McGovern of South Dakota, who ran an anti-war campaign against Republican incumbent President Richard Nixon, but was handicapped by his outsider status, limited support from his own party, the perception of many voters that he was a left-wing extremist and the scandal that resulted from the withdrawal of vice-presidential nominee Thomas Eagleton.

Supporting paragraphs: United States vice-presidential debate, 1976 Walter Mondale
Answer: 1984