[cnn-photo-caption image= http://i.cdn.turner.com/cnn/2008/images/05/27/art.obama0527.ap.jpg
caption="Sen. Obama is gearing up for the last three Democratic contests."]
(CNN) - Barack Obama will close out the primary season on Tuesday with a campaign event at the site of the Republican convention.
His campaign announced on Saturday that the Illinois senator will team up with his wife Michelle at a rally at the Xcel Energy Center in St. Paul, the same arena which will house the 2008 Republican National Convention in September.
Obama's rally will take place as Montana and South Dakota close out the Democratic primary season on Tuesday. Thirty-one delegates are at stake in those two states.
Minnesota is considered a battleground - or swing - state that both parties will fight for in the general election.