Slideshow: Tim Pawlenty on the trail

1 Tim Pawlenty looks on as the man he wanted to replace, President Barack Obama, addresses the White House Governors Ball in the State Dining Room on Feb. 21, 2010 in Washington, D.C. 
2 Tim Pawlenty and "Fox & Friends" co-anchor Gretchen Carlson talk at the "Fox & Friends" at FOX Studios on January 12, 2011 in New York City. 
3 Tim Pawlenty is interviewed on the radio at the Iowa State Fair Aug. 12, 2010 in Des Moines, Iowa, several months before he formally announced his run for president. 
4 Pawlenty, left, jokes with Joe Vallieres following a pick-up hockey game, Friday, March 11, 2011 in Concord, N.H. as he ramped up his presidential campaign. 
5 Tim Pawlenty talks to reporters after participating in a U.S. Chamber of Commerce summit on "the role of free enterprise in job creation" at the chamber May 3, 2010 in Washington, D.C. 
6 Tim Pawlenty waves to supporters after speaking at the Conservative Political Action Conference annual meeting Feb. 19, 2010 in Washington, D.C. 
7 Tim Pawlenty announces that he is running for U.S. President at the State Historical Building May 23, 2011 in Des Moines, Iowa. 
8 Tim Pawlenty signs copies of his new book, "Courage to Stand," at a Barnes and Noble bookstore Jan. 31, 2011 in West Des Moines, Iowa. 
9 Tim Pawlenty stops at each table to visit with members of the Waukee Area Chamber of Commerce during their annual dinner at the Marriott Hotel Jan. 30, 2011 in West Des Moines, Iowa. 
10 Tim Pawlenty answers questions after speaking at the Cato Institute on May 25, 2011, in Washington, D.C. 
11 From left, Rick Santorum, former two-term senator from Pennsylvania; Congresswoman Michele Bachmann; former House Speaker Newt Gingrich; former Massachusetts Governor Mitt Romney; Texas congressman Ron Paul; former Minnesota Governor Tim Pawlenty; and entrepreneur Herman Cain address the first 2012 Republican presidential candidates' debate in Manchester, N.H., on June 13, 2011. 
12 Republican presidential candidates Rep. Michele Bachmann, R-Minn. and former Minnesota Governor Tim Pawlenty pose for a photo before the start of the Iowa GOP/Fox News Debate at the CY Stephens Auditorium in Ames, Iowa, Thursday, Aug. 11, 2011. 
13 Former Minnesota Governor Tim Pawlenty and his wife Mary wave to supporters before he spoke at the Iowa Republican Party's Straw Poll, Saturday, Aug. 13, 2011, in Ames, Iowa. 
14 In this Saturday, Aug, 13, 2001, photo Republican presidential candidate and former Minnesota Gov. Tim Pawlenty waves to supporters after he spoke at the Republican Party's Straw Poll in Ames, Iowa. Pawlenty announced Sunday that he is ending his campaign for president.