June 3 (Bloomberg) -- Barack Obama clinched the Democratic presidential nomination on the final night of primaries that brought an end to his historic campaign against Hillary Clinton.

With a rush of commitments from party leaders and delegates won in South Dakota and Montana today, Obama, a first-term senator from Illinois, will become the first black candidate to lead a major U.S. party into the November general election.

``Tonight we mark the end of one historic journey with the beginning of another,'' Obama, 46, said in a speech tonight to a crowd estimated at 32,000 in St. Paul, Minnesota. ``Tonight, I can stand before you and say that I will be the Democratic nominee for president of the United States.''

Clinton, 60, congratulated Obama and his supporters ``for all they have accomplished,'' stopping short of conceding the nomination as the primary campaign drew to a close.

``The question is, `where do we go from here?''' Clinton said in an address delivered from the gymnasium at Baruch College in Manhattan. ``This has been a long campaign, and I will be making no decisions tonight.''

She repeated her stance that she won the larger share of the popular vote and invited her supporters to weigh in on what she should do next.

``I want the 18 million Americans who voted for me to be respected,'' the New York senator said.

Petition Drive

One supporter, Lanny J. Davis, who was special counsel in President Bill Clinton's White House, is starting a petition to urge Obama to pick Clinton as his running mate.

``The Obama people need to recognize how important it is to have her on the ticket to win the White House,'' Davis said.

Clinton told congressional colleagues in a conference call earlier today that she is ``open'' to accepting the vice presidential nomination and that she would take some time to decide how to end her presidential bid.

Clinton won South Dakota's primary tonight while Obama took the contest in Montana. With 90 percent of South Dakota's precincts reporting, Clinton had 55 percent of the vote to Obama's 45 percent. In Montana, Obama had 56 percent of the vote and Clinton 42 percent with 11 percent of precincts reporting.

Obama, a senator from Illinois, said he is a better candidate for having competed against Clinton.

``Senator Hillary Clinton has made history in this campaign not just because she's a woman who has done what no woman has done before, but because she's a leader who inspires millions of Americans with her strength, her courage, and her commitment to the causes that brought us here tonight,'' he said.

Sparring With McCain

Obama and the presumptive Republican nominee, Senator John McCain of Arizona, already have been sparring over Iraq, national security, the economy and other issues that will be at the forefront in the general election.

In a speech tonight in New Orleans, McCain said he expected Obama to be a ``formidable'' opponent and that the November vote will be ``a change election.''

``No matter who wins this election the direction of this country is going to change dramatically'' he said in a speech in Kenner, Louisiana, outside of New Orleans. ``But, the choice is between the right change and the wrong change; between going forward and going backward.''

Appropriating one of Obama's signature lines, McCain said, at several points, that Obama's proposals didn't offer ``change we can believe in.'' That line became a refrain for McCain, before a crowd his campaign estimated at 600, with 1,000 more outside.

Differences

He also addressed criticism from Obama that he would continue the policies of Republican President George W. Bush by highlighted areas where he has broken with the incumbent, particularly over management of the war in Iraq.

Obama gave his address tonight from the site where McCain is to accept the Republican nomination in September and previewed the general election strategy of linking McCain with Bush.

``It's not change when John McCain decided to stand with George Bush 95 percent of the time, as he did in the Senate last year,'' Obama said. ``It's not change when he offers four more years of Bush economic policies.''

Obama's victory in the nomination battle came 16 months after he announced his candidacy at the Old State Capitol in Springfield, Illinois, the state he has represented in the U.S. Senate since 2004. He and Clinton contested 54 primaries and caucuses beginning Jan. 3 in Iowa and ending tonight in Montana.

While Clinton began the race as the front-runner, it was Obama who won the Iowa caucuses. He went on to win 33 caucuses and primaries, though the 19 where Clinton was victorious include large swing states such as Pennsylvania and Ohio.

To contact the reporters on this story: Catherine Dodge in Washington at Cdodge2@bloomberg.net; Kim Chipman in Washington at kchipman@bloomberg.net;

Last Updated: June 3, 2008 23:44 EDT