Van Os, a Democrat and fiery orator, chose the state Capitol to celebrate the 170th anniversary of the Texas Declaration of Independence.
"The purpose is to declare independence from cronyism, corruption, corporate government and Bushite tyranny, just like our forbearers did in 1836 when they declared independence from despots and tyranny," Van Os said during a break.
Scandals involving bribery and corruption in Congress, as well as lobbyists' heavy influence in Texas and campaign finance problems in the state, have grabbed people's attention, Van Os said.
"People want control back of their democracy and self-government," he said.
He said about 50 people gathered around him at 1 a.m. Saturday near the south steps of the Capitol.
"We had a lot of high-minded interaction and discourse about the meaning of the declaration of independence and the meaning of constitutional government and the powers in the Bill of Rights," Van Os said.
Corruption and greed are nothing new in government, Van Os said when asked about Democratic control of state government in past years.
"The political culture that encourages corruption and cronyism in our political process has been growing and getting increasingly worse for probably the last 30 years," he said. "People know that their ownership of their government is getting ripped off."
Ricky Forrest of Alvin said he was drawn to the scene by a flier announcing Van Os' oratorical marathon.
"I think it takes a lot of guts to do what he's doing, to say what he's saying — to express himself in such contradicting terms from the current administration and their policies," Forrest said. "I live and breathe the opportunity to speak politics."
Forrest said he knew he had to go to Austin to participate.
"I would've felt stupid if I didn't come," he said. "I felt stupid for coming, but I came."
Van Os, the only Democrat running for attorney general in the party's primary Tuesday, will face GOP incumbent Greg Abbott in November.
Van Os said he plans to conduct 24-hour speeches throughout Texas, including at a Cinco de Mayo event in San Antonio.
"I'm going to roll from county seat after county seat and do this in front of courthouses."