A federal law says states and localities with a history of discrimination cannot change any voting procedures without first getting approval from the Justice Department or a federal court in Washington. Yet Texas is asking the Supreme Court to allow the use of new, unapproved electoral districts in this year's voting for Congress and the state Legislature.

The outcome of the high court case, to be argued Monday afternoon, could be another blow to a key provision of the Voting Rights Act. In 2009, the justices raised doubts about whether Southern states still should need approval in advance of voting changes more than 40 years after the law was enacted.

The case also might help determine the balance of power in the House of Representatives in 2013, with Republicans in a stronger position if the court allows Texas to use electoral districts drawn by the GOP-dominated Legislature.

The complicated legal fight over Texas' political maps arises from the state's population gain of more than 4 million people, most of them Latino or African-American, in the 2010 census, and involves federal district courts in Texas and Washington, as well as the Supreme Court. It has come to a head now because Texas needs to be able to use some maps to hold elections this year.

The state has so far failed to persuade three judges in Washington, including two appointees of Republican President George W. Bush, to sign off on new political maps adopted by the Legislature. The justices jumped into the case at Texas' request after judges in San Antonio who are hearing a lawsuit filed by minority groups drew their own political lines for use in the 2012 elections.