Republican Presidential candidate Donald Trump applauds while speaking at a rally in Raleigh, N.C., on Tuesday. (Gerry Broome/AP)

Attorneys for a GOP delegate on Thursday argued that he has the right to vote his conscience at the national convention despite a state law that requires him to vote for the winner of the Virginia presidential primary — Donald Trump.

Carroll “Beau” Correll Jr., a lawyer from Northern Virginia, made his case as part of a contentious federal court battle that has galvanized GOP delegates across the country who are loath to nominate the celebrity billionaire.

The case is playing out days before party activists gather in Cleveland to begin revising rules and preparing for the official nomination of a presidential candidate at the national convention.

Thursday’s six-hour-long hearing involved dueling experts who discussed the minutiae of Republican National Committee rules. Judge Robert E. Payne of the U.S. District Court for the Eastern District of Virginia is expected to rule next week on the challenge to a state law that requires delegates to vote on a first ballot for Trump, who won about 35 percent of the vote in the state’s March 1 primary.

Even if Correll wins the case and the state law is tossed, it’s unlikely to have a practical impact. The nomination will be governed by RNC rules adopted at the convention.

A whole host of influential Republicans have decided not to attend July's Republican National Convention in Cleveland. (Peter Stevenson/The Washington Post)

But Correll, who was co-chair of Sen. Ted Cruz’s campaign in Virginia’s 10th Congressional District, said a victory would nevertheless be of “great symbolic importance” to Republicans who worry that Trump cannot beat presumptive Democratic nominee Hillary Clinton. Many Republicans have bristled at Trump’s bombastic style and say his unconventional campaign strategy could cost their party the White House.

“The national spotlight is on this convention,” Correll told reporters outside the federal courthouse in Richmond. “Take a minute and ask yourself if we can do a lot better than Mr. Trump. We can do a lot better than Mr. Trump.”

Correll said his lawsuit could have “ramifications and reverberations” in other states, but he would not say how the case fits into a national strategy. One of his attorneys said the case is being funded by the Citizens in Charge Foundation but declined to elaborate.

Trump’s campaign is closely monitoring the case.

Donald F. McGahn II, a former chairman of the Federal Election Commission and an election law attorney for Trump, sat in the courtroom for the hearing but declined to comment.

In his lawsuit, Correll contends that the law conflicts with RNC rules and violates his civil rights.

Lawyers in the office of Attorney General Mark R. Herring (D) defended state law alongside eight Virginia Republican delegates and Trump supporters who petitioned to be part of the case.

The group includes John Fredericks, a conservative radio show host from Chesapeake, Va., and Eugene A. Delgaudio, a former Loudoun County supervisor and conservative firebrand who survived a 2014 recall effort.

They presented testimony from Jesse R. Binnall, a professional parliamentarian working for the Trump campaign, who said the RNC’s current rules require Virginia to allocate delegates proportionally based on the primary results. That would give 17 delegates to Trump, 16 to Sen. Marco Rubio (Fla.), eight to Cruz, five to Ohio Gov. John Kasich and three to retired neurosurgeon Ben Carson.

Correll’s attorneys presented testimony from Erling “Curly” Haugland, a Republican national committeeman and co-author of “Unbound: The Conscience of a Republican Delegate.”

Haugland, who makes a living selling swimming pool supplies in North Dakota, said he believes that RNC rules allow delegates to vote their consciences.

“Delegates can frequently be taken advantage of if they don’t know their rights,” he said.

Early in the hearing Payne, the judge, seemed to anticipate a drawn-out legal fight ahead when he told lawyers, “This may be the first railroad station on your journey.”