A tough Texas law requiring voters to show photo identification at the polls discriminates against low-income blacks and Hispanics, a federal court ruled Thursday, wiping out for the November election a measure championed by conservatives and setting up a potential U.S. Supreme Court showdown.

In Washington, a three-judge panel unanimously ruled that the 2011 law imposes "strict, unforgiving burdens on the poor" and noted that Texas' racial minorities are more likely to live in poverty.  It was the state's second major loss in court in three days, coming after a separate federal panel ruled Tuesday that Texas' Republican-dominated Legislature failed to avoid "discriminatory purposes" when drawing new maps for congressional districts and both houses of the state Legislature to reflect the Texas' booming population. The voter ID decision could set a precedent for upcoming legal challenges to similar laws in other states.