John Thune was born in Pierre, S.D., and now resides in Sioux Falls. He earned a bachelor's from Biola University and a master's in business administration from the University of South Dakota.
Thune was a legislative aide to then-U.S. Sen. James Abdnor from 1985 to 1987. He followed Abdnor to the Small Business Administration, where he served from 1987 to 1989.
Thune has served as executive director of the state Republican Party, state railroad director and executive director of the South Dakota Municipal League.
He won election to South Dakota's open U.S. House seat in 1996, serving three terms. He ran unsuccessfully for the U.S. Senate in 2002.
He was elected to the Senate in 2004, defeating then-Senate Democratic Leader Tom Daschle. Thune was re-elected in 2010 without Democratic opposition.
Thune and his wife, Kimberley, have two daughters.
John Thune won re-election to a second U.S. Senate term in 2010 without opposition. The South Dakota Democratic Party failed to find anyone to run against Thune, likely due to the widespread perception that he could not be beaten and the fact that he had amassed $6.5 million in campaign funds by April 2010.
Thune considered running for president, but announced in February 2011 that he would not enter the race. He became an early backer of Mitt Romney's bid for the Republican presidential nomination in November 2011, and has been mentioned as a possible running mate for Romney.
Thune has been considered a rising star in the Republican Party since he defeated the Senate's then-top Democrat to win a return trip to Congress. He speaks frequently around the nation.
Thune was elected in December 2011 to the No. 3 spot in the Senate Republican leadership. He is conference chairman, which means he helps communicate the GOP's message on health care, government spending and other issues through the news media.
In his second term, he has sought to repeal the 2010 health care reform law and to cut the federal deficit. But he also has paid attention to South Dakota issues, seeking more money to fight the mountain pine beetle infestation that is killing trees in the Black Hills and fighting possible federal regulations that would have prevented young people from doing many jobs on farms and ranches.
He has been a contender in South Dakota's two most expensive Senate races. He narrowly lost his first bid for the U.S. Senate when he challenged Democratic Sen. Tim Johnson in 2002, but he ran successfully against then-Senate Democratic Leader Tom Daschle two years later in a race that drew extensive national attention and funding.
Daschle was vilified by top Republicans as an obstructionist to President George W. Bush's agenda and was the GOP's top Senate target in 2004.
Thune's campaign painted Daschle as out of touch with South Dakotans' values. Thune had won three House terms, the last two with more than 70 percent of the vote, and his statewide popularity matched Daschle's.
After Thune was elected to the Senate, he and Sen. Tim Johnson put the bitterness that characterized their 2002 race behind them. The two have often worked together on issues important to South Dakota, and they sometimes travel together.
Thune lined up with President Bush on most major issues, such as tax cuts, controlling spending, property rights and defining marriage. He also has worked with Democratic members of South Dakota's delegation on agricultural issues, such as country-of-origin labeling and the promotion of ethanol and wind energy.
While Thune generally agreed with President Bush and Republican leaders on tax and defense issues, one of the most noteworthy aspects of his first year in the Senate was a cooperative effort featuring politicians of both parties to save Ellsworth Air Force Base in western South Dakota, which had been targeted for closure.
Thune voted in October 2008 for the $700 billion bailout of the nation's financial industry, but he voted against the February 2009 economic stimulus package passed by Congress. Thune said he agreed something had to be done, but he believed the stimulus bill was too costly and would not create enough jobs.
"It's not fair to our children and grandchildren. Our government has to learn to live within its means," he said at the time.
Thune has worked to provide more law enforcement officers on Indian reservations in an attempt to reduce crime in those areas.
Committee Assignments: Commerce, Science, and Transportation; Agriculture, Nutrition, and Forestry; Budget; Finance
American Conservative Union Rating: 75
Americans for Democratic Action Rating: 15
John Thune is not up for re-election in 2014.
(Last updated by The Associated Press on June 11, 2014.)