RICHMOND, Va. (Reuters) - A Virginia law requiring voters to show photo identification went on trial in federal court on Monday, challenged by Democratic Party activists who allege it throws up barriers to voting by minorities and the poor.

Lawyers defending the 2013 Virginia law said it prevented voter fraud. The trial in U.S. District Court is one of several voting rights legal battles as Democrats and Republicans square off before November’s presidential and congressional elections.

The Democratic Party of Virginia and two party activists are suing the Virginia State Board of Elections and want Judge Henry Hudson to strike down the law.

Attorney Bruce Spiva, representing those challenging the measure, said the photo ID law was an effort to hamper the Democratic Party in the state.

It creates “irrational hoops that people have to jump through” and has a “disproportional impact on people of color,” Spiva said.

Mark Hearne, an independent counsel for the state attorney general, dismissed the allegations.

“It is impossible to show a suppressive effect on minorities from the photo ID law,” Hearne said. He added the law was an effort to protect against voter fraud.

In 2008, President Barack Obama was the first Democrat to carry Virginia in more than 40 years, partly because of turnout among black, Latino and young voters.

Obama took the state again in 2012. The Republican-controlled legislature passed the voter ID law the following year.

Josephine Okiakpe, a black woman from Northern Virginia, testified she was unaware of the new ID law when she tried to vote in 2014.

She presented identification including a voter registration card, a Medicare card, a Social Security card and a utility bill showing she was a state resident, but could not cast her ballot.

“It made me feel very frustrated and bitter,” Okiakpe said.

Hudson dismissed two provisions in the original lawsuit last year. One had argued that the photo ID requirement resulted in long lines at polling stations, and the second sought to overturn a state requirement restoring voting rights to non-violent felons individually.

Attorneys have suggested the trial could last a week or more.