For the third time this week, a new poll has the presidential race in North Dakota neck-and-neck, prompting RealClearPolitics and Pollster.com to move the state into the tossup category.

A Research 2000 poll released Friday had Barack Obama and John McCain in a dead heat at 45 percent. The poll sampled 9 percent more Republicans than Democrats and found independents swinging to Obama by 7 percent.

On Monday, The Forum newspaper released a poll showing a statistical tie with Obama at 45 percent and McCain at 43 percent. On Thursday, the North Dakota United Transportation Union released a poll showing a statistical tie with Obama at 44 percent and McCain at 41 percent.

North Dakota was a tied race early this summer until McCain’s pick of Sarah Palin as his running mate skewed the polls decidedly toward McCain. With three polls now showing a tied race, North Dakota has become a battleground and erased the gains McCain made with his vice presidential pick. North Dakota has not gone for a Democrat since Lyndon Johnson’s landslide win against Barry Goldwater in 1964.