Washington (CNN) Hillary Clinton accused four potential GOP presidential rivals by name of being "scared of letting citizens have their say" as she called Thursday for every American to automatically be registered to vote.

Clinton told an audience at the historically black Texas Southern University that she supports the concept of signing every American up to vote as soon as they're eligible at age 18, unless they specifically opt out. She called for expanded access to polling places, keeping them open for at least 20 days and offering voting hours on evenings and weekends.

For the first time in her campaign, she attacked her likely opponents by name as she laid into four GOP governors -- Texas's Rick Perry, Wisconsin's Scott Walker, Florida's Jeb Bush and New Jersey's Chris Christie -- telling them to "stop fear-mongering about a phantom epidemic of voter fraud."

"All of these problems voting just didn't happen by accident," she said. "And it is just wrong -- it's wrong -- to try to prevent, undermine and inhibit Americans' right to vote."

The former secretary of state's move to put voter access front and center in the 2016 presidential campaign highlights a contrast with laws implemented by GOP-controlled legislatures in states like North Carolina, Texas, Wisconsin and Florida that cut down on early voting times and tighten voter identification rules.

The Supreme Court also ruled in 2013 that a key aspect of President Lyndon Johnson's Voting Rights Act of 1965 is no longer constitutional.

"What is happening is a sweeping effort to disempower and disenfranchise people of color, poor people and young people from one end of our country to the other," Clinton said.

In her 2008 campaign, Clinton rarely addressed voting rights. But Democrats have fretted that policies imposed by GOP state legislatures in recent years could dissuade African-Americans and those in urban areas from voting, cutting into crucial blocs of Democratic support in swing states.

The Democratic frontrunner highlighted the issue in a heavily political speech as she received an award in the name of Barbara Jordan, a pioneer African-American lawmaker and civil rights leader.

"Forty years after Barbara Jordan fought to extend the Voting Rights Act, its heart has been ripped out," Clinton said. "I wish we could hear her speak up for the student who has to wait hours for his or her right to vote; for the grandmother who's turned away from the polls because her driver's license expired; for the father who's done his time and paid his debt to society but still hasn't gotten his rights back."

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Her complaints about the Republican governors: Perry signed a law that courts later ruled intentionally discriminated against minority voters; Walker signed one that made voting more difficult for college students; Christie rejected an expansion of early voting; and Bush oversaw a purge of the state's voter rolls.

And she attacked the nation's high court for its 2013 ruling on the Voting Rights Act as well as its 2010 decision on campaign finance laws.

"We need a Supreme Court who cares more about the right to vote of a person than the right to buy an election of a corporation," Clinton said.

While the speech appears to be good politics, the likelihood of achieving universal voter registration is questionable even to people who support it.

Rob Richie, the executive director of the Center for Voting and Democracy, a group in favor of universal registration, said Thursday that the "very decentralized" voting systems in the United States make it "feasible" but "difficult."

The primary problem: The United States does not have a national ID system like other countries that have universal voter registration.

"There is not a simple single approach because we do not have this simple, singular ID that connects us," said Richie, noting that instead of registering to vote nationally, in the United States, you register with your state.

One solution to the problem would be to implement a national identification card, said Richie. The problem: Groups like the American Civil Liberties Union and others are vehemently against a national ID, calling it a "slippery slope" to surveillance and monitoring citizens.

Clinton supports the concept of universal registration, but not a specific method, an aide said.

The former first lady has long been a supporter of voting rights: She helped register voters in Texas' Rio Grande Valley during the George McGovern's failed 1972 presidential run and as a senator introduced legislation to make Election Day a national holiday and reduce lines at polling stations.

Clinton's top campaign lawyer, Marc Elias, has also taken on the fight by filing lawsuits challenging voter restriction laws in Ohio and Wisconsin. He told The New York Times on Wednesday that "we should all want to ensure that all eligible voters can exercise their right to vote and have their vote counted."

Clinton's aides have said that they are aware of the lawsuits and are supportive of their goals.

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The changes have drawn Democrats -- including lawyers close to Clinton and the Democratic National Committee -- into a voting rights fight that some African-Americans, like South Carolina Democrat Bakari Sellers, are calling "the greatest challenge of our generation."

Obama won 93% of African-American voters in 2012 and 95% in 2008, according to exit polls. Some Democrats worry that Clinton needs a similar performance with African-American voters and disenfranchisement is an issue that Democrats hope will activate that base.

The first few months of Clinton's campaign have seen a number of events and trips focused on African-American voters.

In her first speech as a candidate, Clinton called for mandatory police body cameras across the country and end "era of mass incarceration," an issue that connected with African-American activists concerned about black men dying at the hands of law enforcement.

Clinton also focused on a minority-owned business in her first trip to South Carolina, a state with a sizable African-American population that overwhelmingly picked Obama over her in the 2008 primary.