Jon Tester is currently the junior Senator from the state of Montana, serving a first term that begin in 2006. Before he begin his political career, he was a farmer, first conventional and later organic. He comes from the town of Havre, in the highline, in the eastern, prairie part of Montana, which is rural and conservative, even by Montana standards.
To explain Tester's 2006 victory, a bit about Montana politics has to be explained. Montana was considered to be a bedrock conservative state through most of the 1990s and early 2000s, mostly over what could be described as "cultural" differences. Montana's two senators were Max Baucus, who joined the Senate in 1978, before the Democrats were stereotyped as an urban, coastal party, and Conrad Burns, who was, to put it bluntly, almost a caricature of a Montana redneck. In 2000, Brian Schweitzer, who later become governor, tried to unseat Burns and lost. Brian Schweitzer, despite being quite liberal, was able to come much closer to unseating Burns than most people thought possible, mostly because he was able to connect culturally with the people of Montana.
By 2006, either because they had gotten better at projecting their image, or because Montana's demographics were shifting, the Democratic party was able to succeed with the same formula, and a different candidate. Jon Tester has a buzz cut and some missing fingers from a farming accident. He was born and grew up in a rural part of Montana, on a farm his grandfather homesteaded. Speaking as a dirty hippie, Jon Tester looks like he might be the type of person who would shoot me for looking at his pickup truck wrong. Because he was able to connect with rural voters (and play to Montana's Libertarian sensibilities, with such statements as "I don't want to weaken the Patriot Act, I want to repeal it!"), while still giving Montana's liberal voters a way to get rid of Conrad Burns, he managed to squeak out a narrow victory in the 2006 election cycle.
Having won the seat, it is still too soon to see exactly what type of positions Tester is going to take. His populism and manner seem to reflect his actual views and attitude, not merely a campaign trick. But whether he will be able to channel those into a workable political agenda remains to be seen. It is also unclear how easy it will be to hold on to his seat in the 2012 election, since Montana may snap back to being more conservative, especially if Obama's agenda proves to be unsuccessful or unpopular.