FACTBOX: How experienced are U.S. presidential candidates?

(Reuters) - Critics say Sen. Barack Obama, who claimed the Democratic nomination on Tuesday, has too little governing experience to become U.S. president.

Following is a list of Democratic and Republican nominees for president since 1980, and their political backgrounds prior to running for the White House.

2008 - Obama was elected in 2004 to the U.S. Senate from Illinois, where he served eight years in the state Senate. His Republican opponent will likely be John McCain, a prisoner of war in Vietnam who represented Arizona in the U.S. House of Representatives for four years before being elected to the U.S. Senate in 1986.

2004 - Democrat John Kerry failed in his bid to unseat Republican President George W. Bush. At the time, Kerry was in his fourth term as a senator from Massachusetts. He previously served as that state's lieutenant governor and is a decorated Vietnam War veteran.

2000 - Bush, who was elected governor of Texas twice and was the son of former President George H.W. Bush, defeated Democratic Vice President Al Gore. Gore, the son of a U.S. senator, served in the House and Senate from Tennessee for 16 years before being picked in 1992 to run for vice president.

1996 - Democratic President Bill Clinton won re-election against Bob Dole, who represented Kansas in the U.S. Senate for 27 years and became the longest-serving Republican leader in that chamber. A decorated World War Two veteran, Dole also was the Republican vice presidential candidate in 1976.

1992 - Clinton defeated Republican President George H.W. Bush. Clinton, who also once headed the centrist Democratic Leadership Council, was governor of Arkansas for 12 years and also served a term as that state's attorney general.

1988 - Bush, the sitting vice president, defeated Democrat Michael Dukakis, who had been elected three times as Massachusetts governor. Bush had served two terms in the U.S. House of Representatives from Texas and as U.N. ambassador, chief envoy to China and CIA director before being picked in 1980 as Ronald Reagan's vice president running mate.

1984 - President Reagan won re-election against Democrat Walter Mondale, a former two-term senator from Minnesota who served as President Jimmy Carter's vice president from 1977 to 1981.

1980 - Reagan, who served two terms as California governor following a career as a movie star, beat Carter, the Democratic incumbent. Prior to becoming president, Carter served one term as governor of Georgia and was a state senator and peanut farmer.

(Compiled by Matthew Bigg; editing by Michael Christie and David Wiessler)