It's almost over, isn't it?

That seems to be all anyone wants to know from Sen. Hillary Clinton's presidential campaign, but the only person who truly knows isn't telling.

"I'm sort of a day-at-a-time person, and we'll see when Tuesday and the day after Tuesday comes," Clinton said on board a late-night flight to South Dakota, where she planned to spend the last full day of the primary season campaigning.

The last two Democratic primaries are on Tuesday in South Dakota and Montana.

"My political obituary has yet to be written, and we're going forward," Clinton said. "It is not over 'til it's over."

By most accounts, it is over.

Barack Obama, who holds what experts call an insurmountable lead in delegates for the Democratic presidential nomination, plans a rally on Tuesday to launch his campaign for the November election against Republican John McCain.

Clinton's political obituary has been written many times. "The End" declared the online Drudge Report under a photograph of Clinton campaigning in Puerto Rico at the weekend.

The same campaign trip inspired a headline on the online magazine Salon.com saying: "Clinton seemed to be campaigning in an alternate reality."

Campaigning on Monday in Rapid City, Clinton greeted patrons at a diner and complimented the life-sized bronze statues of U.S. presidents standing on city streetcorners.

"You should be there!" a supporter shouted to her.

As the nomination moved likely beyond Clinton's reach, her staff was busily declaring her victorious.

"She has more votes," spokesman Mo Elleithee insisted in Puerto Rico. "Hillary Clinton has received more votes than any other Democrat in this race for president."

That point is in dispute, since it includes vote totals in Michigan, where Obama's name was not on the ballot, and in Florida, where neither candidate campaigned. It also leaves out states won by Obama that used a caucus system where individual votes are not tallied.

In any case, the popular vote does not count in the nominating process. What counts are delegates to the national convention, and Obama leads both in elected delegates and superdelegates who are free to support whomever they like.

MISTY-EYED

"One thing about superdelegates is that they can change their minds," Clinton reminded reporters after the Puerto Rico primary, which she won by a wide margin.

The Clinton campaign, which wants to convince superdelegates that she is the stronger candidate against McCain, hoped to use the Puerto Rico result to support its argument but lower-than-expected turnout weakened the case.

Other cracks were appearing in a campaign that had stayed remarkably optimistic despite the political reality.

"I'm starting to get a little misty-eyed," one staffer whispered to another while Clinton visited a San Juan bakery.

The candidate, whose persistence could be viewed either as fierce determination or outright obsession, seemed to flag a bit in Puerto Rico.

Her standard campaign speech lasts nearly a half hour but she addressed a rally in San Juan for just a few minutes.

A campaign trip on the back of a truck in Puerto Rico was cut short as darkness fell and supporters along the route ceased to materialize.

Her victory party in San Juan, a city of more than 400,000, attracted only a few hundred people. The same afternoon, Obama drew more than 2,000 supporters to the South Dakota town of Mitchell, population roughly 15,000.