Morrison is being extremely unestimated he has won state-wide election twice since 2000. While Tester has only won a few (not sure on how many) state senate elections in a traditionally democratic district. Morrison won in 2000 by 50-45% and in 2004 by 56-44%.
2000 was an open seat and he was the incumbent in 2004, correct? There are a lot of Democrats and Republicans elected statewide in states that traditionally lean to the opposite party, but that does not mean they can defeat an incumbent straight out... even Conrad Burns.