By Lauren Etter, Janan Hanna and Mark Niquette Bloomberg

Mazie Butler Ferguson, 72, remembers picking cotton for neighbors in 1964 so they could take time to study for a reading test they needed to pass before they could register to vote. This year, the Greensboro, North Carolina, resident found herself on a new front in the battle for ballot access.

Election officials in Guilford County, home to half a million people, opened a single polling site compared with 16 four years ago, with no weekend voting, except for the Sunday before Halloween. As a result, the number of ballots cast was down at one point by 90 percent compared with a similar moment in 2012.

“We struggled so hard for them to open early voting and we wanted souls to the polls every Sunday,” said Ferguson, who is a Baptist minister. “We were able to get them to give us one date.”

North Carolina has been at the center of a pitched conflict over ballot access that began several years ago in Republican statehouses. It shifted to courtrooms and is now being waged at polling places in the final days of the 2016 election. Democrats are filing last-minute court challenges and drawing attention on the campaign trail to what they say are Republican efforts to suppress votes. On Thursday, a federal judge ruled that Republican poll watchers can’t travel freely throughout Pennsylvania to monitor the voting, as party leaders had urged.

Speaking to a crowd at the University of North Carolina at Chapel Hill on Wednesday, President Barack Obama characterized the state’s voter identification law as “one of the worst voter-suppression laws in the country – here, in North Carolina. Not back in the 1960s, now.”

Hours before he spoke, Obama’s Justice Department warned state election officials to stop improperly purging voters from the rolls. A lawsuit this week by the NAACP claimed those officials were illegally striking voters if letters mailed to their address were returned.

Kim Westbrook Strach, executive director of the North Carolina State Board of Elections, defended the law. “Challenged voters receive due process prior to any cancellation,” she said in a court filing Wednesday.

North Carolina is just the starkest example of such skirmishes. In recent days, a voter-rights group in Texas sued county officials for hanging polling-place signs that said a photo ID was required, even though a federal court struck down that requirement months ago. In Wisconsin, officials have been accused of cherry-picking early-voting sites based on the perceived leanings of the electorate. In Ohio, rights groups waged last-minute challenges to rules that allow counties to dismiss provisional ballots for reasons such as names written in cursive rather than print.

“Getting a win in the courthouse is really only the first step toward there being any difference on the ground for voters,” said Jennifer Clark, counsel for New York University’s Brennan Center for Justice, which studies election laws.

This year, Republican presidential nominee Donald Trump has tried to rally volunteer poll watchers to forestall what he calls a “rigged” election and Democrat Hillary Clinton has warned voters to beware of intimidation. In Pennsylvania, a judge has granted Democrats a hearing – the day before the election – for their lawsuit accusing Trump aide Roger Stone of plotting to disrupt Philadelphia voting.

“The partisan conflict over election laws and procedures has been ratcheting up over the last 15 years or so,” said David Kimball, political science professor at the University of Missouri-St. Louis. “It’s just ratcheted up another level, particularly in swing states where both parties see the presidential contest is on the line.”

Republicans have been rewriting rules in many states to require identification to stamp out in-person vote fraud, which is surpassingly rare. Democrats say the new laws are actually meant to suppress their support. Sixty percent of U.S. voters live in the 32 states that require photo ID, according to the Congressional Research Service.

In North Carolina, a battleground state, Republicans took control of both houses of the legislature in 2010 and the governor’s office two years later, ending two decades of Democratic rule. Since then, Democrats have been ousted from county election boards and in 2013, lawmakers passed one of the nation’s strictest ID laws, cut early voting by a week and scaled back Sunday voting.

An appeals court in July invalidated the measure, ruling it was targeted at “African Americans with almost surgical precision” and reinstated early voting to 17 days. Republicans resisted.

“We will not continue to have one side — the Democrats — set the voting rules forever,” Dallas Woodhouse, the executive director of the North Carolina Republican Party, said in an interview.

In an August e-mail to county election officials, Woodhouse wrote that compliance required early voting at only one site, and that Sunday voting wasn’t a necessity. In recent elections, many black congregations organized “souls to the polls” efforts, capitalizing on high church attendance with outings to the polls afterward.

“Many of our folks are angry and are opposed to Sunday voting for a host of reasons including respect for voter’s religious preferences, protection of our families and allowing the fine election staff a day off,” Woodhouse wrote. “Six days of voting in one week is enough. Period.”

More than a dozen counties offered only one site for the first week of early voting, which began Oct. 20. That led to longer waits.

“There were lots of examples of people leaving lines,” said Allison Riggs, an attorney at the Southern Coalition for Social Justice in Durham. “This would not be even remotely acceptable in the future, but, given the time pressures, we were trying to triage and tourniquet the worst situations.”

Statewide, early voting by whites had increased by 16 percent through Tuesday compared with the same point in 2012, while voting by blacks was down 13 percent, said J. Michael Bitzer, a political-science professor at Catawba College in Salisbury. Ballot returns are up 8.5 percent from Republicans, almost 40 percent from unaffiliated voters, but down by about 2 percent from Democrats, he said.

The new rules were “a major factor,” Bitzer said.

Ferguson of Greensboro has memories of knocking on doors in the South as a member of the Congress of Racial Equality, which was a prime mover in the civil-rights movement. She spent so much time getting others to register that she almost forgot to herself. She felt proud to cast her ballot for Lyndon B. Johnson.

These days, she has a weary heart.

”I’m so disappointed,“ Ferguson said. ”I really believed that I was going to be able to see these problems solved in my lifetime.“