Question: Who was a candidate for the Libertarian Party's 2012 nomination for President of the United States, that unsuccessfully challenged during his tenure, the fourth-ranking Republican leader in the House?

Context paragraphs:
Sue Jeffers: Sue Jeffers (born October 3, 1956) was a candidate for Ramsey County Commissioner, a small business owner, and former candidate for Governor of Minnesota.  Jeffers challenged incumbent Tim Pawlenty for the Republican Party nomination in the 2006 Minnesota gubernatorial election, after declining endorsement from the Libertarian Party of Minnesota.  The Republican Party of Minnesota declined to consider her endorsement at the 2006 State Convention, citing her previous affiliations with the Libertarian Party of Minnesota.

R. J. Harris: Richard Jason Satawk "R. J." Harris (born November 16, 1972) is a United States Army National Guard warrant officer, politician, law student and former Air Traffic Controller.  He was a candidate for the Libertarian Party's 2012 nomination for President of the United States.  In 2010, he unsuccessfully challenged incumbent Tom Cole for the Republican Party nomination in the primary election for Oklahoma's 4th congressional district.  He ran as an independent candidate for the same congressional seat in 2012.

Libertarian Party presidential primaries, 2016: The 2016 Libertarian Party presidential primaries and caucuses allowed electors to indicate non-binding preferences for the Libertarian Party's presidential candidate.  These differed from the Republican or Democratic presidential primaries and caucuses in that they did not appoint delegates to represent a candidate at the party's convention to select the party's nominee for the United States presidential election.  The party's nominee for the 2016 presidential election was chosen directly by registered delegates at the 2016 Libertarian National Convention, which ran from May 26 to 30, 2016.  The delegates nominated former New Mexico Governor Gary Johnson and former Massachusetts Governor Bill Weld.

Harry Browne presidential campaign, 2000: The 2000 presidential campaign of Harry Browne, investment banker and 1996 nominee of the Libertarian Party began on February 14, 2000.  On the third night of the 2000 Libertarian National Convention (July 3), Browne won the nomination on the first ballot over Don Gorman, Jacob Hornberger, and Barry Hess, with 493 votes (56.15% of the ballot), becoming the first Libertarian Party candidate to be nominated twice for President.  Art Olivier (former mayor of Bellflower, California) was nominated as Vice President on the 2nd ballot.

Texas's 8th congressional district: Texas District 8 of the United States House of Representatives is a Congressional district that includes Montgomery County and Walker County.  It includes much of the northern outlying areas of metro Houston.  The current Representative from District 8 is Kevin Brady and has been since 1997.  For the 2014 election cycle Craig McMichael, a veteran of the Marine Corps, and network engineer had challenged and lost to incumbent Kevin Brady in the Republican Primary.  In the 2014 General Election, Brady faced off against the Libertarian Party candidate, Ken Petty of Spring, Texas, who won his nomination in the Libertarian District Convention.  No Democrat ran.  In the 2016 election, the 20-year incumbent was challenged by 3 challengers: Andre Dean, Craig McMichael, and Steve Toth.  As of August 2017, Brady is expected to face Democrat Steven David in the 2018 election as well as Independent candidate Todd Carlton.  David is the first Democrat to challenge Brady since the 2012 election.

Political positions of Gary Johnson: Gary Johnson was the governor of New Mexico from 1995 to 2003 and ran for president in 2012 and 2016.  In December 2011 he announced he would pursue the presidential nomination of the Libertarian Party for the 2012 general election.  The Libertarian National Convention in May, 2012 chose Johnson as the party's candidate.  In November 2014, Johnson announced he would pursue the presidential nomination of the Libertarian Party for the 2016 general election.  Johnson has taken positions on many political issues as revealed through his public comments, his gubernatorial record, his Our America Initiative and his campaigns to win the Republican and Libertarian nominations.

Tom Cole: Thomas Jeffery Cole (born April 28, 1949) is the U.S. Representative for Oklahoma 's 4 congressional district , serving since 2003.  He is a member of the Republican Party.  He is a Deputy Majority Whip.  The chairman of the National Republican Congressional Committee (NRCC) from 2006 to 2008, he was, during his tenure, the fourth-ranking Republican leader in the House.  As of 2015, Cole – a member of the Chickasaw Nation – is one of only two registered Native Americans in Congress (the other being fellow Oklahoman Markwayne Mullin).

Gary Johnson presidential campaign, 2012: The 2012 presidential campaign of Gary Johnson, the 29th Governor of New Mexico, was announced on April 21, 2011.  He declared his candidacy for the 2012 Republican Party nomination for President of the United States.  On December 28, 2011, Johnson withdrew his candidacy for the Republican nomination, and declared his candidacy for the 2012 presidential nomination of the Libertarian Party.  The 2012 Libertarian National Convention was held during the first weekend of May 2012.  On May 5, 2012, after promoting his libertarian-oriented political positions to delegates, Johnson received the most votes at the convention and became the official 2012 Libertarian presidential nominee.  On November 6, 2012, Johnson received just under 1% of the popular vote in the general election, amounting to more than 1.2 million votes, more than double what the Barr/Root ticket received in 2008.  This was the most successful result for a third-party presidential candidacy since 2000, and the best in the Libertarian Party's history by vote number at the time.  (Johnson ran again in 2016 and received nearly four times his 2012 vote total.)

Bill Redpath: William Bruce "Bill" Redpath (born October 9, 1957) is an At-Large Representative on the Libertarian National Committee, immediate past Treasurer and a former National Chairman of the United States Libertarian Party and immediate past Chairman of the Libertarian Party of Virginia.  A six-time candidate for public office, most recently he was the 2014 Libertarian Party nominee for the US House of Representatives in Virginia's 10th Congressional District.

History of the Libertarian Party (United States): The Libertarian Party of the United States was formed in Colorado Springs in the home of Luke Zell by a group of individuals led by David Nolan on December 11, 1971, after several months of debate among members of the Committee to Form a Libertarian Party, founded July 17.  The formation was prompted in part by price controls and the end of the Gold Standard implemented by President Richard Nixon.  The Libertarian Party viewed the dominant Republican and Democratic parties as having diverged from what they viewed as the libertarian principles of the American Founding Fathers.  This group included John Hospers, Edward Crane, Manuel Klausner, Murray Rothbard, Roy Childs, Theodora (Tonie) Nathan, and Jim Dean .

Supporting paragraphs: R. J. Harris Tom Cole
Answer: Richard Jason Satawk "R. J." Harris