No one. Bill Clinton had won re-election to a second term in 1996.
In the 2000 election, Al Gore (Democrat) ran against George W. Bush (Republican). In the 2004 election, John Kerry (Democrat) ran against George W. Bush (Republican). George W. Bush won both the 2000 election and the 2004 election.
Lloyd Bentsen who was a Senator from Texas.
Bush defeated Dukakis in 1986 but lost to Clinton in 1990.
George H. W. Bush ran against Dukakis in 1988 and won 54% of the popular vote. The electoral vote was Bush 426, Dukakis 111. (Reagan ran against Carter in 1980 and against Mondale in 1984: he did not run against Dukakis.)
George H. W. Bush defeated Dukakis in 1988.
John Kerry was the Democratic candidate against Bush in 2004.
Al Gore
Yes. Michael Dukakis ran on the Democratic ticket against George H. W. Bush in 1988.
George H. W. Bush ran against Ronald Reagan in the 1980 Republican primaries, but lost. Bush would eventually become Reagan's Vice President.
They were all Vice-Presidents of the United States. George Bush was Veep under Ronald Reagan from 1981-1989 and eventually won the presidency and served from 1989-1993. Dan Quayle served as Veep under George Bush from 1989-1993. He ran for and lost the presidency in 2000. Al Gore was Veep under Bill Clinton from 1993-2001 and the 2 beat Bush and Quayle in the 1993 Election. Gore ran for the presidency in 2000 and narrowly lost by a few hundred votes in Florida but won the Popular Vote.
No one. Bill Clinton had retired from the presidency in 2001.