Obama’s march past the delegate threshold appeared inevitable throughout the day as the remaining undecided superdelegates came over to his side in force, and the results from the last two contests – South Dakota and Montana – seemed academic while still adding delegates to Obama’s total.

“Tonight, I can stand before you and say that I will be the Democratic nominee for President of the United States,” Obama said in front of thousands of enthusiastic supporters.

In victory, the Illinois senator sought to first unify what appears to be a fractured party, lavishing praise on vanquished rival Sen. Hillary Rodham Clinton (N.Y.), who did not concede defeat while also commending Obama.

“Sen. 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,” Obama said in his remarks at the Xcel Center in St. Paul, Minn.

“Our party and our country are better off because of her, and I am a better candidate for having had the honor to compete with Hillary Rodham Clinton,” he added.

Clinton went out with a victory of sorts as she won the South Dakota primary. In that win, however, Obama secured more than enough delegates to put him over the top.

Hitting that point home, an hour after the polls closed in South Dakota, Obama won the Montana primary and the support of another 26.5 delegates, including several members of Congress.

Clinton’s Tuesday night win, however, was yet another reminder that Obama has struggled to win the support of working class and rural white voters. The former first lady’s victory in South Dakota reinforced what the primaries in places such as Ohio, Pennsylvania, West Virginia and Kentucky had already shown.

As it became clear that Obama would clinch Tuesday night, rumors and reports began to swirl through cable news networks and the Internet that Clinton was “open” to joining Obama on the ticket.

While Obama in his remarks was clearly taking steps to try to assuage the anger of the more than 17 million people who voted for Clinton throughout the nomination battle, he pivoted quickly toward the general election and his next opponent, who also signified Tuesday night that the next battle has already begun.

McCain spoke earlier in the night from New Orleans, where he outlined his plan of attack against Obama, attempting to seize the message of change from Obama and make his case for representing change coupled with experience.

Clinton had attempted a similar tack against Obama, but in the end it was the Illinois senator who was viewed as the change candidate.

McCain, however, repeatedly accused Obama, as he has in recent weeks, of being willing to meet with American’s enemies instead of its military leaders and embracing big-government solutions and higher taxes.

“In just a few years in office, Sen. Obama has accumulated the most liberal voting record in the Senate,” McCain said. “But the old, tired, big government policies he seeks to dust off and call new won't work in a world that has changed dramatically since they were last tried and failed. That's not change we can believe in.”

Obama, speaking from the site of this summer’s Republican convention, acknowledged McCain’s military service and the Arizona senator’s criticisms of his youth and short time in the Senate.

“They will come here to nominate John McCain, a man who has served this country heroically,” Obama said. “I honor that service, and I respect his many accomplishments, even if he chooses to deny mine. My differences with him are not personal; they are with the policies he has proposed in this campaign.”

The theme of Obama’s remarks on McCain was to portray the presumptive GOP nominee as offering a third term of President Bush’s administration.

The Illinois senator accused his Arizona counterpart of wanting to continue tax cuts for the wealthy, ignoring Americans without health insurance and continuing the Iraq War without end.

On that last note, Obama waded into territory that has drawn the constant ire of McCain’s campaign and the Republican National Committee (RNC) when he said “what’s not an option is leaving our troops in that country for the next hundred years.”

“We must be as careful getting out of Iraq as we were careless getting in - but start leaving we must,” Obama said.

Clinton’s remarks, which preceded her assertion that she would not make any decisions about her campaign Tuesday night, were at times short of conciliatory despite her praise for Obama early in the speech.

Clinton noted that with 53 contests finished – she spoke before the polls had closed in Montana – that she was “carrying the popular vote with more votes than any primary candidate in history.”

The Obama campaign has disputed that calculation because there were no vote totals taken in caucuses, contests where he had a decided if not overwhelming advantage.

That said, Clinton also noted that she “won the swing states necessary to get to 270 electoral votes,” pointing to states like Ohio and Pennsylvania.

Obama’s win was lauded throughout the political universe Tuesday night for its historical nature.

The Illinois senator climbed another rung on a short career ladder in meteoric fashion by securing the nomination, smashing a racial barrier in the process.

Having exploded onto the national political scene with his highly regarded speech at the 2004 Democratic nominating convention, Obama’s trek from state senator to U.S. Senator to his party’s standard-bearer has happened in a blink.

Beginning with his win in the Iowa caucuses, a victory that quelled the concerns about many of his supporters about whether he could win over white voters, Obama astonished many analysts who had long thought Clinton would be the inevitable nominee.

Obama, 18 months and 54 nominating contests later, now moves on to the general election against McCain, one history making run behind him and another potentially in front of him.