Controversy over laws prohibiting members of the Electoral College from voting their conscience rather than the presidential candidate who won their state appears headed to the U.S. Supreme Court.

A challenge is likely now that a federal appellate ruling this week split the courts over whether states can lawfully remove or sanction “faithless electors,” or those who stray. An unsual number did so in 2016 in the election of President Donald Trump.

Harvard Law professor Lawrence Lessig, who founded the progressive non-profit Equal Citizens, said Electoral College outcomes are going to get closer, raising the possibility of a small number of electors changing an outcome.

“Whether you think that’s a good system or not, we believe it is critical to resolve it before it would decide an election,” Lessig said.

His group, which represents the plaintiffs in two conflicting cases, intends to ask the Supreme Court to take up the issue. A petition could come as early as October.

The push to allow more freedom to electors comes amid frustrations among progressives with the Electoral College, which has twice since 2000 handed the presidency to Republicans who lost the popular vote. They were George W. Bush and Trump.

The popular vote for president and vice president actually is a vote for a slate of electors from each state who make up the Electoral College. There are 538 electors, the number of which is based on the size of the congressional delegation for each state plus three for the District of Columbia.

More than half of the states and D.C. have laws requiring electors to vote a certain way, according the National Conference of State Legislatures. And electors customarily certify the popular result from their respective states. Some have strayed throughout U.S. history, but they’ve never altered the outcome of a presidential race.

But the seven who didn’t vote the expected way in 2016 revived the controversy, which included fresh legal challenges in Colorado and Washington.

The Colorado case involved Michael Baca, who the state removed as an elector and nullified his vote for then-Ohio Gov. John Kasich, who ran in the Republican primary.

Baca had earlier pledged to uphold state law and support the popular vote winner in his state, which was Democrat Hillary Clinton.

The Denver-based U.S. Court of Appeals for the Tenth Circuit backed more freedom for presidential electors when it found that Colorado violated Baca’s constitutional rights. It said he had standing, or the legal authority, to challenge his removal from office and cancellation of his vote.

Colorado Secretary of State Jena Griswold said the ruling takes power away from the state’s voters, and indicated she intends to vigorously, and quickly, defend the people’s voice—including at the U.S. Supreme Court, if necessary.

Supreme Court intervention seems more likely given that the Tenth Circuit’s ruling conflicts with a May decision from the Washington Supreme Court. It upheld $1,000 fines for Democratic electors who voted for former National Security Adviser Colin Powell in order to prevent Trump from winning the electoral vote.

The state high court also upheld the fines against an elector who voted for a member of the Yankton Sioux Nation.

Lessig’s group wants both cases heard together.

A high court ruling striking down limits on faithless electors wouldn’t have a broad impact as a practical matter, said Elizabeth Slattery of the conservative Heritage Foundation.

“There have been fewer than 170 ‘faithless electors’ in our nation’s entire history going all the way back to the 1796 election, and they have never affected the outcome of an election,” Slattery said.

But St. Mary’s University School of Law Dean Stephen M. Sheppard said the “movement of faithless electors is likely to become more common as party unity becomes less so.”

The Colorado case is Baca v. Colo. Dep’t of State, 10th Cir., No. 18-1173, 8/20/19.