Sen. John Thune doesn't buy the recent buzz that he may be Mitt Romney's "dark horse" vice presidential pick."'Dark horse' usually means you are way back in the pack somewhere. I'm not sure that's a good thing," he said during an interview Wednesday in his Capitol Hill office. "Very few dark horses actually win the race."The South Dakota senator is little-known nationwide but is a well-respected power player in Washington and a hero of conservatives, having won his Senate seat eight years ago by knocking off the most powerful Democrat in the chamber.Thune, 51, has been the subject of much vice presidential chatter the past few weeks, and he says he knows why his name comes up in these conversations."There's a sense, when push comes to shove, they are looking for somebody from a different part of the country," he said. "Maybe somebody who is balance, in some ways, on the ticket and maybe somebody with Washington experience on the ticket."He added that several other contenders who have been mentioned fit that profile, so he isn't planning on leaving the Senate anytime soon. "I like the job I have. I'm not aspiring to any other job," he said."I've also said you don't rule any options out, because if you are in public life because you want to make a difference … obviously, you have to be open to those kind of possibilities."So is he being vetted by the Romney campaign?"There's a process. We don't talk about the process," he said, sinking into his winged-back chair and waving the question away with his hands.(...) Unlike many Republicans who waited to see how the Republican primary shook out, Thune endorsed Romney in Iowa in November 2011. His support of Romney in the weeks before the caucuses there was seen as critical, particularly in western Iowa, where many conservatives remained skeptical of Romney at that time.His native South Dakota is a reliably red state and has only three electoral votes. But Bob Haus, a veteran Iowa-based GOP strategist, said adding Thune to the ticket could win points in the Hawkeye State."I think Thune is a pretty well-known commodity in Iowa. He's very well respected," Haus said. "He's tall, energetic, telegenic, and I think next to (Vice President) Joe Biden, that would be pretty stark."Romney surrogate and former New Hampshire governor John Sununu said in an interview with National Review last month that there was "no question" Thune was "on the short list" of those being considered for the position.