A scheme under consideration in Virginia to rig the Electoral College in Republicans’ favor could well violate a key provision of the Voting Rights Act, experts on the law say. But that very provision is itself under challenge by the GOP, and could be struck down by the Supreme Court later this year.

A Republican bill that would allocate Virginia’s electoral votes based on the popular vote in each congressional district cleared its first hurdle in the state legislature Wednesday. Had the bill been in effect in the last election, Mitt Romney would have won 9 of Virginia’s 13 electoral votes, despite losing the popular vote in the state to President Obama by nearly 5 percentage points.

Republicans have raised versions of the idea in several other blue states where they currently have state-level control, including Wisconsin, Ohio, Michigan, and Pennsylvania. If all four states approved the plan, future GOP presidential candidates would get a major—and anti-democratic—leg up.

But in Virginia, where the plan has advanced the furthest, several voting-rights experts told msnbc.com it could be on shaky legal ground. Section 5 of the 1965 Voting Rights Act requires certain states, including Virginia, to clear any voting changes with the U.S. Justice Department. If the Feds find that the change would have a “retrogressive effect” on minority voters, they can block it.

“Does this change make African-American voters worse off than they were before?” asked Daniel Tokaji, a prominent election-law scholar and a professor at Moritz College of Law at Ohio State University, laying out what he said was the key legal question at issue. “It’s hard to argue it doesn’t.”

“I think there’s a very strong argument to be made that this change has a retrogressive effect on African-American voters in particular and perhaps Latino voters as well,” Tokaji reiterated, adding that the issue had been a subject of online discussion among election-law experts in recent days.

Brenda Wright, a top lawyer at Demos and an expert on voting rights, agreed. “I think there would be strong arguments” that the change harmed minority voters, she said.

And Gerald Hebert, a veteran election lawyer and the former acting head of the Voting Section of the Justice Department’s Civil Rights Division, offered further support for that view. “Any move to reallocate electoral votes on the basis of congressional districts—especially in states with sizeable minority population—raises potential violations of the VRA [Voting Rights Act],” Hebert wrote in an email to msnbc.com.

Because Section 5 only covers states and jurisdictions with a history of racial discrimination, it doesn’t apply to Ohio, Pennsylvania, Michigan or Wisconsin. Tokaji and Wright both said it might be possible to challenge the efforts there under a different section of the Voting Rights Act, but it would be a much heavier lift, in part because the burden of proof would be on those challenging the law. By contrast, under Section 5, Virginia would have the burden of proving that the change didn’t hurt minority voters.

On its face, that seems like a difficult argument to make. By switching to a system based on congressional districts, the plan would drastically reduce the power of the state’s African-American voters, who tend to be packed into a small number of districts. That’s why civil-rights groups are up in arms. The NAACP’s Wade Henderson, on msnbc’s The Melissa Harris-Perry Show Sunday, called it “a diabolical scheme.”

But opponents of the plan won’t want to count on Section 5—because it may not be around much longer. The Supreme Court has said that this session, it will take up a challenge to the provision, being brought by Alabama and other southern states, who argue that the progress they’ve made since the 1960s on civil rights means it’s no longer needed. The Roberts Court hasn’t generally been supportive of voting rights, and many court observers expect Section 5 could be struck down.

The Supreme Court is expected to rule on Section 5 in June. There could be even more than we thought riding on that decision.

Late Update, 2:25pm: A Virginia Republican on the committee set to consider the Electoral College change, State Sen. Ralph Smith, says he opposes it. Smith’s opposition, along with that of all Democrats, would ensure the bill dies in committee.

Late Late Update, 3:51pm: And Gov. Bob McDonnell also has come out against the bill, making it a non-starter.