San Antonio: Hillary Clinton, once seen as a lock for the Democratic nomination, battled on Saturday in possibly the last weekend of her presidential campaign, struggling to reverse a tide of money and momentum that has turned dramatically toward Barack Obama.
The New York senator stormed across Texas, questioning Obama's readiness to lead, particularly on national security issues.
"You are in effect hiring the next president," Clinton told supporters at a get-out-the vote rally at a San Antonio high school. "What you've got to decide is: Who do you want to hire?"
The Illinois senator touched down in Rhode Island - his first campaign visit to the tiny state - as well as Ohio.
Obama targeted Clinton with some of his harshest criticism of the campaign, knocking her for taking money from federal lobbyists, voting for "George Bush's war in Iraq" and voting in favour of a bankruptcy bill that made it "harder for families to climb out of debt".
The three states and Vermont will vote tomorrow in contests that could effectively settle the Democratic fight - or extend the race well into springtime or beyond.
In a campaign that has frequently defied expectations, a consensus emerged as the candidates caromed across the country: Clinton must win Texas and Ohio to have any serious hope of sustaining her bid to become the nation's first female president. A split decision would not suffice, analysts said, and winning narrowly may not help.
"We're reaching a point where - not all voters, but lots of voters - are starting to feel it's time for the party to coalesce around a candidate," said Geoffrey D. Garin, a veteran Democratic pollster who is unaligned in the contest. "The Clinton campaign has to have a compelling and persuasive reason to go on. She's got to come out of Tuesday with people believing that she has a realistic path to the nomination."
The political math seems to work against the former front-runner. Obama has opened a small but growing lead of delegates to the Democratic National Convention. Unless Clinton starts winning big, and polling in Texas and Ohio suggests that will be difficult, she could have a tough time overtaking Obama.
"We have to maintain our delegate lead and make sure that we don't get blown out in those two states," Obama told reporters earlier this week as he campaigned across Texas. "If we come out of the four contests on Tuesday with a gap in the delegate count of 100 or 150, which we have right now, then I continue to believe that we will go to the convention with the most earned delegates and believe that we should be the nominee."
After reeling off 11 consecutive victories, Obama has two things going for him as he vies to become the nation's first black president: the proportional awarding of delegates - which means he can keep adding to his number even if he loses the popular vote to Clinton - and the campaign calendar.
After Tuesday, the race shifts to Wyoming, which holds its caucuses on Saturday.
Complicated Process
Texas gets to vote twice
It's a voting procedure unique to Texas, and it's likely to further muddy the waters in the tight Democratic contest to be the party's presidential nominee. Here they get to vote twice.
"Texans like to do things big," said Kenneth Molberg, from the Texas State Democratic Executive Committee, with a laugh.
So on Tuesday all eligible voters in the state will be able to take part in the Democratic primaries which will start at 7am and end at 7pm.
But things are not over once the primaries have closed. Far from it. Instead the doors will open again at 7.15pm for Texas's caucuses, which are called a convention here.
Roughly two-thirds of Texas's total 193 Democratic delegates are allocated according to the results of the primaries in the state's 31 electoral districts, and the remaining third come from the caucus process. The Democratic Party of Texas has published a four-page booklet trying to explain the rules of the caucuses, which previously only committed political die-hards paid much attention to.
"They're not well-understood, they're not well-documented and the rules have been followed quite loosely in the past," April Lloyd, the assistant primary director for Harris County, told the Chronicle.
Usually only 5,000 Texans turn up to caucus in Harris County, but this year's figure could be a staggering 100,000, the paper said.
And the results from the caucuses are not set to be known until June 7.
