AUSTIN (AP) _ Texas Democrats packed into county conventions Saturday as supporters of Barack Obama and Hillary Clinton fought again to win delegates in a complex and long-running presidential caucus system.

Early results tallied by The Associated Press showed that Obama had 839 delegates selected to go on to the state convention, compared with Clinton's 833 delegates. That's out of about 7,300 delegates expected to be selected at senate district meetings across the state.

Because of the huge Democratic turnout in Texas' primary and caucuses on March 4, just registering delegates took hours at some conventions. At large conventions in Houston, Dallas and Austin, which were expected to last into the night, arguments erupted and confusion set in as complaints were lodged about the legitimacy of some delegates.

Hundreds of increasingly irritable and bored delegates at the Senate District 23 convention in Dallas stood in lines snaking around four hallways as they waited to receive a delegate credential. Police kept people from jumping out of turn. Several called the process "chaos."

"People are so confused," said Michelle Powell, 18, five hours after she arrived at the convention. "Nothing is organized."

Jacqueline Bell, a precinct chair, said, "The democratic process is messy."

Credentials committees heard challenges against the way certain delegates were selected at precinct caucuses in early March. Frustrated delegates shouted at credentials committee members in Dallas.

Many of the challenges were brought by Clinton supporters questioning the validity of Obama delegates. The Clinton campaign said it wouldn't lodge any challenges itself but that it was helping supporters who would. The campaign previously said it was aiding supporters with legal advice and guidance on their challenges.

Obama was also lodging challenges in some counties over the complex formulas used to determine delegate counts, said campaign spokesman Josh Earnest.

"This math gets pretty complicated pretty quickly," he said.

But Earnest said that unlike the Clinton campaign, the Obama campaign wasn't challenging the seating of particular delegates.

"They're engaged in a coordinated strategy to challenge our delegates and we're not," he said. "It's disappointing to see the Clinton campaign throw up these obstacles."

As he drove between Democratic conventions in Georgetown and Waco on Saturday to rev up supporters, Clinton adviser Terry McAuliffe said that the Clinton campaign has "not raised any of the challenges. A lot of our supporters have."

McAuliffe said in some cases handwriting on sign-in sheets at the March 4 caucuses was obviously the same handwriting but for different names. One woman in a wheelchair wasn't let into a caucus, and one Clinton supporter was told she didn't have to stay, he added.

"It disenfranchises people," McAuliffe said, comparing the Texas caucuses to Michigan and Florida voters being disenfranchised.

Heading to senate district conventions in Austin, some delegates got fed up waiting at least an hour in traffic to reach the Travis County Expo Center. Some abandoned their cars on the side of the road and walked the rest of the distance.

Travis County officials extended the morning sign-in period because so many of the thousands of delegates hadn't gotten the chance to register.

Jenny Magar of Austin, a 47-year-old delegate for Obama, was not put off by the waiting or by the organization of her convention.

"The old-timers are going to be prepared for it, and the new-timers are going to be curious," she said.

Clinton supporter Winston Nguyen, 21, felt discouraged at the largely pro-Obama Senate District 13 convention in Houston. Nguyen said he planned to protest the results because he didn't think the delegates' credentials were properly checked. Some Clinton backers broke into tears because they were not treated right, Nguyen said.

"I think they feel that the party is getting ripped apart," he said.

Two Obama supporters at that Harris County convention, 54-year-old Adib Saafir and 29-year-old Katrina Moore, said they each received text messages before the convention telling them to wrongly go to a caucus at a school in Fort Bend County. They said the note was signed "Ken the planner."

By the time they found the right convention in Houston, it was too late to register.

"I just want to participate, that's it," Saafir said. "I signed up to be a delegate and I wanted to participate, but when I got here I was too late."

Obama has fared better overall in caucuses this year, winning 13 to Clinton's 3.

Texas Democrats hold both a presidential primary and caucus. Clinton won the March 4 primary with 51 percent to Obama's 47 percent, earning her 65 national convention delegates to Obama's 61.

The state's caucus began immediately after polls closed primary night and quickly devolved into chaos in many parts of the state after an unprecedented estimated turnout of more than 1 million Democrats. An incomplete and unofficial count by the Texas Democratic Party showed Obama was leading Clinton in caucuses 56 percent to 44 percent on election night.

A total of 67 national convention delegates are ultimately at stake in the Texas caucuses.

Obama entered Saturday's Texas conventions leading the national race for delegates, 1,623 to 1,499. It will take 2,024 delegates to secure the Democratic nomination. Those totals could change after this round of the Texas caucuses.

Associated Press writers John Porretto in Houston and Paul J. Weber in Dallas contributed to this report.

Copyright 2008 The Associated Press.