According to this story, former U.S. Senator Larry Pressler of South Dakota may run for the Senate again as an independent in 2014. He was in the Senate 1978-1996. He was always elected as a Republican, but in both 2008 and 2012 he endorsed President Obama. Thanks to Gene Berkman for the link.
Interesting but at the same time somewhat confusing. The article doesn’t really say what his positions are on issues other than his friendliness to the Native Americans which is certainly commendable.
This article from Politico in 2008 indicates Sen. Pressler became estranged from the Republican Party because of the Iraq War and the growth of government spending and the deficit under President Bush
http://www.politico.com/news/stories/1008/14963.html
The article indicates he thinks of himself as a moderate conservative.