US Senator Hillary Clinton?s poll numbers are slipping and each day seems to bring news of waning support but a display of stubborn optimism surrounds the candidate who faces do-or-die contests in her presidential bid today.

Despite Clinton?s declining popularity and growing momentum for rival Democrat Senator Barack Obama, aides and supporters reveal nary a glimpse of the doom and gloom that many pundits predict for the former front-runner now struggling in her bid to become the Democratic Party?s presidential nominee for November?s election.

The former first lady, who would be the country?s first female president, faces nominating contests today in Texas and Ohio, where if she loses, many say, she could be forced to leave the race. ?The mood is very upbeat and focused, and I think that comes right from the top,? said campaign spokesman Doug Hattaway. ?She?s very clear-headed, focused on the task, doesn?t let any ups and downs get us down.? That?s what Clinton says, too. ?We have to win today, that?s not a surprise to any of you, and we are going to win on Tuesday,? she told supporters and campaign volunteers over the weekend in Texas. ?Don?t sleep between now and the time those caucuses are over.? On board her campaign plane, her voice hoarse after months of speeches and interviews, Clinton told reporters, ?I?m just focusing on doing the best I can.? ?I feel good about our campaigns,? she said. ?We?ll find out how people evaluate our candidacies today.?

What happens behind the campaign?s closed doors, of course, could be an entirely different story. Her top aides do not often travel on campaign trips, where their demeanor would be most visible. Some US media have carried reports of her staff bickering and blaming one another for campaign woes. Clinton has lost the past 11 primaries to Obama.

Those who have covered Clinton over the years see her as tireless and not likely to flag in the face of adversity. In her first Senate campaign in New York, she liked to cite Harriet Tubman, a heroic former slave who helped other slaves escape to freedom. ?If you hear the dogs, keep on going. If you hear gunfire, keep on going. If you hear shouts and footsteps, keep on going,? Clinton would say, quoting Tubman.

Clinton volunteer Carolee Moore, a retired social worker in San Antonio, said she had stopped paying attention to the news.

?ou know what our attitude is? Don?t look at it if it bothers you,? she said.