America's presidential primary season ends Tuesday with contests in Montana and South Dakota. But, as we hear from VOA's Michael Bowman, events in Washington will likely determine whether Democrats will have a presumptive nominee within the next 24 hours.

Pedestrians in Billings, Mont. pass by campaign headquarters and  cardboard cutout of Barack Obama, holding vote, 03 May 2008

Five months of primary contests are coming to an end as voters go to the polls in the last two Democratic presidential primaries. The frontrunner, Illinois Senator Barack Obama, had been favored to win both handily, but the latest polls suggest the race has tightened in those states.

Obama and New York Senator Hillary Clinton are vying for a total of 31 pledged delegates in Montana and South Dakota. Even if Obama wins both states, that will not give him enough for an outright win of the Democratic nomination.

As a result, the Illinois senator hopes to get the backing of more of the party elders and elected officials, the so-called "super delegates." By most estimates, Obama needs the support of roughly two dozen super delegates out of the more than 150 that have still not announced their preference.

Monday, Obama picked up the endorsement of another powerful super delegate, Democratic Congressman and Majority Whip James Clyburn, who formally annonced his decision early Tuesday on NBC's Today show.

"He [Obama] is elevating the political rhetoric, he is elevating our party, he is energizing our country," said Clyburn. "He is bringing new voters to the process, people who are in thirst of a new vision."

Obama is planning a major address in Minneapolis, Minnesota, shortly before polls close in Montana and South Dakota.

Sen. Hillary Rodham Clinton speaks at a campaign event in Huron, South Dakota, 29 May 2008

Meanwhile, Hillary Clinton, who trails Obama by more than 150 delegates, will be addressing supporters in her home state of New York. There have been conflicting reports from officials close to the Clinton campaign about whether she intends to drop out of the race. Monday, while campaigning in South Dakota, Clinton struck a seemingly wistful tone as she stated a goal that extends beyond her political fortunes: preserving the hopes and dreams of the American people.

"I want to be sure that that dream stays alive for my daughter, for your children and your grandchildren," Clinton said. "And I do not believe that dream is given to you. I believe it is earned."

On the Republican side, Arizona Senator John McCain is already his party's presumptive nominee. Both parties will formally nominate their presidential choices at party conventions in late August and September.