(Mary Altaffer/AP Photo)

Green Party candidate Jill Stein and her vice presidential running mate Cheri Honkala were arrested at the Hofstra University debate site today as they protested their exclusion from the second presidential debate.

Stein and Honkala were jailed for disorderly conduct around 3 p.m. when they were blocked by police officers as they attempted to enter the debate hall, according to Stein's campaign manager Ben Manski.

Manski said that it was unclear when they would be released, but they could remain jailed until midnight. The Nassau County Police Department said that it was unclear when Stein and Honkala might be released.

"The arrest was outrageous and shouldn't be tolerated in a country that is a leading proponent of democracy," Manski told ABC News. "They knew that there was the possibility that they would be arrested. Their intention was to enter the premises and bear witness to the mockery of democracy that is tonight's debate," he said.

The Green Party has long complained that the Commission on Presidential Debates attempts to "rig elections" in favor of the two major political parties by excluding third party candidates from debates. Stein and Honkala also planned protests at the first presidential debate in Denver.

Stein, a licensed physician, is on the presidential ballot in 38 states or 85 percent of the ballots, her campaign says.

The Commission on Presidential Debates was formed in 1987 to administer general election debates.

In addition to the constitutional criteria to be eligible for the presidency, the Presidential Debate Commission requires that candidates have a mathematical possibility of achieving the 270 electoral college votes necessary to be elected, and the candidates must have at least 15 percent support in public opinion based on the average of five national polls in order to participate.