By Ellen Wulfhorst

SUNRISE, Florida (Reuters) - The souvenir vendors outside Hillary Clinton's campaign appearances have added a new button to their wares that reads "Chelsea in 2016" with a picture of the former first daughter.

Attention, whether from button sellers or the national media, is leaving the fading presidential candidacy of Sen. Hillary Clinton behind as the former front-runner faces what most see as impossible odds to win the Democratic nomination.

Now in the spotlight is her rival, Sen. Barack Obama, who has solidified his lead among Democrats and is setting his sights on Republican candidate John McCain in the November election.

While Obama and McCain spar -- the two clashed this week over whether the United States should talk to leaders of hostile nations -- Clinton's struggle to collect votes in Florida that were cast months ago but invalidated feels like a sideshow.

Obama's milestone victory in Oregon on Tuesday that gave him a majority of pledged delegates to the Democratic nominating convention graced front pages of U.S. newspapers.

Clinton's simultaneous victory in Kentucky, which did little to close her gap with Obama, was a much smaller story.

"The shrinking candidacy of Senator Hillary Rodham Clinton all but vanished from the television set," wrote The New York Times.

Even calls for the former first lady to drop out have abated, whether because she seems less of a threat to damage Obama or because she paid them no heed. Despite a campaign deeply in debt, she vows to compete through the last primaries on June 3.

After the mixed results in Oregon and Kentucky, Clinton soldiered on this week in Florida which, along with Michigan, saw its January primaries invalidated because they were held earlier than Democratic Party rules allowed.

Clinton won both primaries and wants the votes counted and the delegates seated.

She maintains she would lead Obama in the popular vote if both states were counted. Although delegates select the party nominees, contenders such as Clinton hope to win uncommitted superdelegates, who can back any candidate.

WRITTEN OFF

In Florida, Clinton's speeches were part civics lesson, part call to action and part comparison to the state's voting recount in 2000.

Voting confusion in south Florida left the contest between Republican George W. Bush and Democrat Al Gore undecided, but a controversial U.S. Supreme Court decision resolved the race in favor of Bush. Gore won the popular vote.

"We are still arguing, aren't we, for counting all the votes back in 2000, and we should be just as passionately arguing for that principle today, here in Florida and in Michigan," Clinton told retirees in Boca Raton.

As she spoke, an elderly man sitting behind her, directly in the eye of television cameras, yawned deeply, rubbed his eyes and battled to stay awake.

Despite Clinton's efforts, Obama holds what almost everyone outside her campaign and her hardcore supporters sees as a nearly insurmountable mathematical lead in party delegates.

So much so, many political observers have written off her campaign as a lesson in recent history.

"Hillary Clinton's Defeat: A Historic Triumph" declared a headline on the Huffington Post, a news and politics Web site.

On Slate, a commentary site, correspondent John Dickerson wrote: "Forget math majors -- what about science?"

"The race for the Democratic nomination -- 'race' is hardly the right word, is it? -- now feels like a quantum physics problem: How long can a body exist in a state approximating motionlessness without actually stopping?" he wrote.

But for supporters like Nora Blake, 85, who listened to Clinton speak at a senior citizens center in Sunrise, Florida, the media and the Democratic Party are to blame for unfairly dismissing the New York senator's candidacy.

"I don't understand why they are so anti-Hillary," said the retiree from Brooklyn, New York. "The Democratic Party is dismissing her, the Democratic National Committee is dismissing her. I think they should all be junked."

Clinton's staff tried to stir up enthusiasm for her ongoing campaign among the exhausted reporters trailing her around Florida and griping that editors at home don't care about any Clinton story unless she dropped out of the race.

"I'm not hearing the excitement," one campaign aide said as the candidate's plane landed in Palm Beach and a second aide launched into a rehearsed speech on Clinton's strategy.

"Did you hear that?" another aide prodded a reporter. "A little bit," the reporter replied.

(Editing by Eric Beech)