(CNN) -- Sen. Hillary Clinton received the most votes in two pivotal Democratic primary contests Tuesday, scoring wins in Texas and Ohio that were considered critical to keeping alive her White House hopes.
Sen. Hillary Clinton is the winner in Ohio and Texas primaries, but trails in the Texas caucuses.
With 99 percent of precincts reporting in Ohio, Clinton had 54 percent of the vote compared to 44 percent for Sen. Barack Obama.
The race was closer in Texas where, with 99 percent of precincts in, Clinton had 51 percent to Obama's 48 percent.
A complicated formula in Texas that weighs delegates more heavily in highly populated areas and includes a caucus that was still being tallied Wednesday afternoon meant the delegate count there remained unclear.
Obama was leading Clinton in the caucus vote 56 percent to 44 percent with 38 percent of the state counted, party officials said.
The party will split 67 delegates between the candidates in proportion to the final caucus results. Watch an I-Report video from a Democratic caucus »
A final tally was not expected until Thursday afternoon, officials said.
"For everyone across America who has been counted out but refused to be knocked out, for everyone who has stumbled but stood right back up and for everyone who works hard and never gives up, this one is for you," Clinton said to a cheering crowd in Columbus, Ohio. Watch Clinton thank backers »
After a month of losses to Obama, Clinton had been expected to do well in Ohio -- where the blue-collar workers who have consistently supported her throughout the campaign make up a large chunk of the Democratic base.
But with polls showing the Ohio contest neck-and-neck in the days leading up to the primary, Clinton got a boost from female voters and those who only recently made up their minds.
According to CNN exit polling, 59 percent of the voters in the state's Democratic primary were women. Those female voters favored Clinton over Obama, 58 percent to 40 percent.
In the past week, Clinton sharpened her attacks on Obama -- questioning whether he has enough experience to lead the nation and attempting to cast doubt on his opposition to international trade agreements that many in Ohio feel have led to job losses.
Poll results suggest it may have worked. Among those polled, 64 percent of those who decided their vote in the last three days chose Clinton.
Clinton was believed to need strong performances in Tuesday's contests in Ohio and Texas to halt Obama's momentum in the race and stay alive in the hunt for the 2,025 delegates needed to win the nomination.
As early returns were counted Tuesday, Obama ran a string of consecutive victories to 12 with a lopsided win in Vermont. With 99 percent of precincts reporting, he led Clinton 59 percent to 39 percent.
But Clinton snapped that streak in Rhode Island. With 98 percent of precincts reporting, Clinton had taken 58 percent of the vote to Obama's 40 percent.
Speaking in San Antonio, Texas, Obama told supporters he expected to hold a similar delegate lead over Clinton after Tuesday's races to the one he held before.
"We know this -- no matter what happens tonight, we have nearly the same delegate lead we had this morning and we are on the way to winning this nomination," he said to cheers and chants of his trademark phrase, "Yes we can." Watch an excerpt of Obama's speech to supporters »
With Texas' delegates still to be awarded, Clinton had picked up 22 delegates after results in Ohio, Rhode Island and Vermont were tallied.
Obama entered the day holding a lead of just over 100 delegates, with 1,369 pledged delegates and superdelegates to Clinton's 1,267, according to CNN estimates.
In Ohio, harsh weather and balloting problems stretched the polling well into the evening.
With polls slated to close at 7:30 p.m., state elections officials decided to extend voting until 9 p.m. in northern Ohio's Sandusky County.
The area was hit by freezing rain for much of the day, and ballot shortages were reported in the Cleveland and Columbus areas -- also causing the polls to be open until 9 p.m.
Texas, with its 193 Democratic delegates, and Ohio, with 141, were the biggest prizes in Tuesday's contests. There were 15 Democratic delegates at stake in Vermont and 21 in Rhode Island.
Texas' results may not be as easy to measure as counting votes.
In what pundits have been calling the "Texas two-step," the state's Democratic Party held a primary election, in which 126 delegates were awarded, and a post-election caucus in which another 67 are at stake.
It's possible for the loser of the primary to win more delegates with a strong showing in the caucuses. Texas' method of awarding delegates in the primary -- with more delegates coming from large population centers like Houston, Dallas and Austin -- further complicates the matter.
As polling places closed Tuesday, Texans reportedly lined up in bigger-than-expected numbers for the caucuses -- in some places lining up in parking lots and overflowing buildings where caucuses were held.
Party officials Wednesday said 1.1 million voters participated in the caucuses.
A CNN I-Reporter in Houston said there were hundreds of people at his polling place -- he said he waited more than an hour just to sign in.
At an Austin caucus, about 800 people showed up -- far outstripping expectations and causing organizers to stand on tables and yell to organize caucus-goers, one voter said.
Clinton supporters had said a strong performance would keep her campaign alive. Weeks ago, former President Clinton predicted his wife would need wins in Texas and Ohio to stay in the race.
"If Hillary Clinton gets out a small win in Ohio and Texas, it will be like Punxsutawney Phil seeing his shadow," said political adviser and Clinton supporter Paul Begala, referring to the six more weeks of winter the groundhog is said to predict.
The Obama campaign, however, said the arithmetic of the delegate count will make it difficult for Clinton to overcome Obama's lead.
"They've had a really bad run and they have to rationalize continuing," said Obama spokesman David Axelrod. "We've won more popular votes and more delegates, and they have to give some rationale for staying in this race." E-mail to a friend