Less than a week after announcing that only two GOP presidential candidates qualified to appear on their ballot, the Republican Party of Virginia has adopted a new measure that may leave voters in the state scratching their heads: a loyalty oath.

On Wednesday the Virginia State Board of Elections approved a request from the Virginia GOP that will require voters to sign a loyalty oath in order to participate in the state's presidential primary on March 6. A spokesman for the state's election board tells ABC News that although some details are still in the works, voters wishing to cast a ballot must take the pledge.

"We're still working out the details for how things will work on election day," says Justin Riemer, spokesman for Virginia's State Board of Elections, "but the instructions state that they must sign before voting."

Voters do not register with a party in Virginia; thus the commonwealth's primary is open to all residents, not just members of the Republican party. The oath, which reads "I, the undersigned, pledge that I intend to support the nominee of the Republican party for president," is intended to deter non-Republicans from participating in the process unless they are serious about supporting the eventual GOP candidate.

"I think there was a desire to try and keep the Republican party for Republicans," explains Kyle Kondik, a political analyst for the University of Virginia's Center for Politics. "It's the one barrier to entry that the Republican party can put up to try and keep voting limited to people in the club."

Kondik points out that the oath, however, is not enforceable from a legal standpoint, since voters are guaranteed the right to a private ballot.

"It's an honor system," says Kondik. "It doesn't have any legally binding authority. People can go to the primary, sign the pledge and then vote for their candidate and then vote for Obama or a third-party candidate in the fall."

Calls to the Republican Party of Virginia for comment were not immediately returned.