WASHINGTON, D.C.

Days before the first Black president takes office, the Supreme Court agreed Friday to consider overturning a key feature of the main federal law that ensures access to the polls by minorities.

The justices said they will review a lower court ruling upholding a provision of the Voting Rights Act that requires all or parts of 16 states with a history of racial discrimination, most in the South, to get approval before implementing any changes in the way elections are held.

In 2006, Congress voted overwhelmingly to extend the measure for another 25 years. The 1965 law was designed to prevent governments from making it harder for minorities to vote.

The high court has upheld earlier extensions of the provision that calls for either the U.S. attorney general or a court to sign off in advance on changes to requirements to hold office, polling places and other issues involving the conduct of elections.

The justices will hear the case in April and probably decide it by June, against the backdrop of a presidential election that was unimaginable when the law was enacted more than 40 years ago.

“The elephant in the room is what to make of the Obama election,” said Nathaniel Persily, professor of law and political science at Columbia Law School, referring to the election of Barack Obama.

“Does the election of the first African-American president undermine the central justification for parts of the Voting Rights Act?” said Persily.

Under Chief Justice John Roberts, the court has looked skeptically at government efforts to take race into account in the assignment of students to public schools and the drawing of electoral districts.

A second case accepted for argument Friday looks at whether a decision by New Haven, Conn., to scrap a promotion exam after too few minorities passed it violates the civil rights of White and Hispanic firefighters who did well enough to advance.