Five months to the day since the Democratic presidential primary season began, it ends tonight with the spotlight trained squarely on Minnesota.

Voters in South Dakota and Montana are choosing between Barack Obama and Hillary Rodham Clinton 147 days after Iowans handed Obama his first, most crucial, victory in what has become a bruising campaign.

Unlike election nights past, neither tonight's winner nor loser will show up in either of the states where they just battled. Instead, Obama is headed to the Xcel Energy Center in St. Paul for one of his patented mega-rallies -- a clear shot across the bow of Republicans who will be holding their national convention at the hall in September. Doors will open at 7 p.m., but Obama is not expected to speak until closer to 9:30 p.m.

Clinton is headed home to New York City, where she will hold what her campaign described as an "election night celebration."

As the final votes of the primary campaign are being cast, Obama almost has the nomination in his grasp, needing only about three dozen to reach the 2,118 he needs to clinch. For Clinton, the math is more unforgiving. She needs about 200 more delegates.

Obama's aides were working furiously Monday to accumulate commitments from enough superdelegates before the polls close tonight to push him over the top, which would make his Xcel appearance a declaration of victory.

Getty Images, Star Tribune
Ask me: Two women raised their hands hoping Sen. Barack Obama would answer their question during a rally Monday in Troy, Mich.

"I don't know what he's going to say," said Minneapolis Mayor R.T. Rybak, who headed Obama's campaign in Minnesota, where he crushed Clinton in the Feb. 5 caucuses. "It's been a long, fascinating campaign, but now it's time for Obama and the rest of America to concentrate on the real issues facing us."

David Axelrod, Obama's chief strategist, was less circumspect Monday, speaking of the St. Paul rally on MSNBC: "Tomorrow night, I think he is going to talk about the road ahead."

Coming off her commanding victory in Puerto Rico on Sunday, Clinton faces an uphill battle today in South Dakota and Montana, where polls have shown Obama leading.

Both candidates spent their last day of primary campaigning by softening their rhetoric against each other.

Obama told voters in Michigan that he and Clinton will be "working together in November." He did not elaborate.

Clinton campaigned in South Dakota, telling supporters in Rapid City: "I'm just very grateful we kept this campaign going until South Dakota would have the last word. What South Dakota decides tomorrow will have a big influence in what people think going forward."

Republicans awaiting Obama's arrival tonight in Minnesota are acting as if Clinton's campaign is over, not once mentioning her in a conference call with reporters. "We're very happy Barack Obama has chosen to end his campaign in Minnesota, a campaign of happy talk and lack of substance," said Ron Carey, chairman of the state GOP.

Carey and Robert M. (Mike) Duncan, chairman of the Republican National Committee, repeated the litany of accusations about Obama's flaws that former White House strategist Karl Rove laid out Saturday in a speech to the state GOP convention: inexperienced, soft on national security, a big-government liberal.

Duncan said the Obama campaign's appearance in the hall where Republicans will have their big bash "shows we picked the right city and the right state. It shows how competitive Minnesota's going to be." McCain is next due in Minnesota on June 19 for a fundraiser and may hold a public event, Carey said.

Rybak countered: "We're saying we'll take the battle for the presidency everyplace -- including where McCain gets the nomination. ... You've had Karl Rove bashing [Obama] and McCain getting free rein [from the news media]. It's definitely time for Barack Obama to say he's had enough and take the battle where it needs to be."

The Associated Press contributed to this report. Bob von Sternberg • 612-673-7184