Despite Thune's building buzz inside the Beltway, he lacked the nationwide name recognition of many of his well-known rivals, especially in key early states like Iowa, New Hampshire and South Carolina.
Thune also has the potential to move up in the Senate, given Senate Minority Whip Jon Kyl's decision to retire after his term ends next year. Thune, who is also a member of Senate leadership as head of the Republican Policy Committee, could move up the leadership ladder next year.
Thune's potential candidacy loomed large in the minds of other possible contenders. His profile, a young, conservative Midwesterner, could have appealed to the same demographics as candidates like former Minnesota Gov. Tim Pawlenty, or even Indiana Gov. Mitch Daniels. Both Pawlenty and Daniels will benefit without Thune in the race.
Although he's passing on the chance to seek the presidency in 2012, Thune is only 50 years old, and he will remain a top contender for a future bid. After running unopposed in his 2010 re-election bid, Thune now boasts a war chest containing more than $7 million -- an already-imposing amount that should continue to increase in the years leading up to the 2016 election.
This post was updated at 1:22 p.m.