NEW YORK - President Barack Obama has warned that Republicans were suppressing the right of African Americans to vote in a way not seen in 50 years.In unusually sharp language, the president accused his political opponents of using the threat of voter fraud as a ruse to deprive Americans of a fundamental right."The stark, simple truth is this," Obama said at the annual convention of the National Action Network, a civil rights organization founded by the Reverend Al Sharpton, a prominent community leader. "The right to vote is threatened today in a way that it has not been since the Voting Rights Act became law nearly five decades ago." Democrats accuse Republican state and local legislatures across the United States of seeking to limit early voting and of introducing punitive identity checks to cut into the core Democratic vote.Obama argued that such efforts were unnecessary because vote fraud was not widespread and said that in effect, they deprived African Americans of rights to equality that many had died to secure."Fifty years ago we put laws in place because of enormous struggles to vindicate that idea, to make our democracy truly mean something," Obama said."That makes it wrong to pass laws that make it harder for any eligible citizen to vote. "It's a fact, this recent effort to restrict the vote has not been led by both parties. It's been led by the Republican Party."Republicans argue that stricter requirements to prove the identify of voters are necessary to protecting the integrity of US elections.But Democrats counter that such measures discriminate against minority voters and the less well off who disproportionately vote Democrat.Obama's call came ahead of mid-term elections in November in which Republicans are eyeing big gains and may take back the Senate for the final two years of the current president's term.Democratic voters are traditionally more loathe than Republicans to turn out in mid-term elections.And Obama's core constituency of African American, Hispanic and younger voters are also seen as less likely to vote without the president on the ballot.Obama's fiery speech came a day after he traveled to Texas to mark the 50th anniversary of the passing of the Civil Rights Act which abolished racial discrimination - at the library dedicated to president Lyndon Johnson who piloted it through Congress.