2009, Rasmussen Reports conducted a hypothetical matchup of Governor John Hoeven against the incumbent. Hoeven led by a large margin, 58% to Dorgan's 36%. 61% of the state still had a favorable view of Dorgan, and if pitted against State Senator Duane Sand, the incumbent led 52% to 37%. Hoeven was challenged in the race by North Dakota State Senator Tracy Potter of Bismarck. Potter received the endorsement of the North Dakota Democratic-NPL Party at its state convention on March 27, 2010. Governor Hoeven and Senator Potter advanced to the November 2, 2010 general election following balloting in North Dakota's primary election, which was held June 8, 2010. Neither candidate faced any significant opposition in the primary election. Ohio Incumbent Republican George Voinovich retired instead of seeking a third term. Republican former Director of the Office of Management and Budget, United States Trade Representative, and Congressman Rob Portman won the open seat. Originally, the election was seen as a toss-up. His experience as a former Bush official was considered to be a big problem for Portman. Both President Barack Obama and Vice President Joe Biden campaigned for Fisher. Television advertisements were very negative. Fisher attacked Portman for helping to ship jobs overseas during his entire political career, backing deals that shipped jobs overseas, and the trade deficit with China, which grew by over $41 billion. Portman claimed in response that most jobs were being lost to other states, not countries. Portman attacked Fisher for supporting Obama's stimulus and cap and trade. Winning the election, Portman received the majority of votes in 82 of 88 counties and in 15 of 18 Congressional districts, including the district of liberal U.S. Congressman Dennis Kucinich. Oklahoma Incumbent first-term Republican Tom Coburn won re-election to a second term. Coburn, a very popular incumbent, promised to limit himself to two terms. Despite his popularity, he did release television advertisements. In 2009, Coburn's approval rating in a PPP poll was 59%, including a 39% approval rating among Democrats. His Democratic opponent is a perennial candidate who did little campaigning. Oregon Incumbent Democrat Ron Wyden won re-election to a third full term. Wyden, a popular incumbent with a 52% approval rating in a July poll, touted bipartisanship and promised to hold town-hall meetings annually in each of Oregon's 36 counties and to open offices outside of Portland and Salem. A Survey USA poll taken a few days before