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?
Sentence (from "Gary Johnson presidential campaign, 2012"): 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.
Relevant evidence: No