Ms. Davis delivered a pep talk to the small gathering of volunteers here before they were sent throughout the city. She said in an interview that Battleground Texas’ get-out-the-vote efforts would make a difference for her campaign. “Texas is not a deep-red state,” she said. “Texas is a state where people have been staying home.”

Mr. Bird said that Ms. Davis, who became a national figure after her 11-hour filibuster against legislation that would make it more difficult to obtain a legal abortion, has helped Battleground Texas by energizing state Democrats. “Everything we do in every election cycle helps our goal,” Mr. Bird added.

But Battleground Texas has learned that registering voters in the state is not quite like anywhere else. Like other Southern states, Texas was a Democratic stronghold until the 1970s, but Jimmy Carter in 1976 was the last Democrat to carry the state. For at least a generation, Democrats have made only marginal efforts to campaign in Texas. Republicans have dominated for so long that much of the data that Obama-style organizing relies on is out of date.

On one volunteer’s list, nearly 75 percent of phone and address records were inaccurate. Much of the group’s work is cleaning up voter rolls. The group’s nearly 17,000 volunteers have made 1,021,863 phone calls.

The work Battleground Texas is doing in 2014 is helping in “building an infrastructure that will exist in 2016, 2018, 2020,” said Jenn Brown, the group’s executive director. “You’re not going to win every election.”

Central to that goal will be persuading the more than two million Hispanics who are eligible to vote but did not in 2012. In 2010, about one million voting-age Hispanics cast ballots for a turnout rate of about 23 percent, compared with about 44 percent among white voters.