"And what is Obamacare?" O'Brien, formerly the state's House Speaker, asked. "It is a law as destructive to personal and individual liberty as the Fugitive Slave Act of 1850 that allowed slave owners to come to New Hampshire and seize African Americans and use the federal courts to take them back to federal… to slave states."
The tea party-backed O'Brien, who is currently exploring a run for Congress, made the remarks at a statue of John Parker Hale, one of the first U.S. senators to take a stand against slavery in the 1800s.
O'Brien continued: "Barack Obama and our allies fooled us long enough to pass a law that is clearly among the worst ever enacted by Congress."
"Bill O'Brien's painful and gross comparison is just the latest in a long line of misleading attacks and rhetoric promoted by the same special interests who opposed health reform in the first place," said Zandra Rice Hawkins, executive director to Granite State Progress said in a statement.
Hawkins said that Americans for Prosperity and its supporters are actively working to make health coverage expansion "as scary and burdensome as possible."
O'Brien's appearance at the event was part of an ongoing, Koch brothers-funded Americans for Prosperity campaign targeting President Barack Obama's signature health care law. The advocacy group recently sponsored an advertisement that asked misleading questions about the impact of the health care law.