Shortly after Nikki Haley announced her campaign for president on Tuesday, footage was released showing the Republican former South Carolina governor saying states have the right to secede from the union.

“I think that they do,” Haley said in the footage, which Patriot Takes, an anonymously run social media account and fundraising Pac which claims to “monitor and expos[e] rightwing extremism and other threats to democracy”, said came from 2010 and featured an unnamed neo-Confederate group.

“I mean, the constitution says that.”

Haley also said she did not think South Carolina should secede.

Haley’s campaign did not immediately respond to a request for comment.

Anthony Michael Kreis, a law professor and political scientist at Georgia State University, said on Twitter: “No, Nikki Haley, the constitution does not provide a right for secession. See, Texas v White (1869). See also, the civil war.”

In December 1860, South Carolina was the first of 11 southern states to secede over the issue of slavery, prompting civil war. Four bloody years of fighting led to the defeat of those Confederate states.

Four years later, Texas v White, a supreme court case, held that states entering the union became part of “an indissoluble relation … as perpetual, and as indissoluble as the union between the original states. There [is] no place for reconsideration, or revocation, except through revolution, or through consent of the states”.

Haley, who is Indian American, ran for governor in South Carolina in 2010 and won a second term in 2014. She came to national prominence in 2015, in the aftermath of a racist mass murder in Charleston, when she ordered a Confederate flag removed from statehouse grounds. The same year, however, she said a statehouse celebration of the anniversary of secession should be allowed to proceed.

Four years later, she provoked controversy when she said the Confederate battle flag had represented “service and sacrifice and heritage” before it was “hijacked” by Dylann Roof, the racist gunman who killed nine people at a historic Black church in 2015.

Haley opposed Donald Trump’s run for the Republican presidential nomination in 2016 but after he won the White House she resigned as governor to become his United Nations ambassador. She resigned from that post in 2018.

Haley originally said she would not challenge Trump for the nomination if he ran in 2024. He did and she changed her mind, announcing her 2024 campaign on Tuesday, ahead of a Wednesday launch in Charleston.

Haley does not score highly in polling but one recent survey showed potential for Haley to split the anti-Trump vote and thereby hand the nomination to the former president.

Patriot Takes said the footage released on Tuesday had been recorded in 2010, 150 years after the South Carolina secession, in the year Haley first ran for governor.

Asked if she would support South Carolina seceding again, Haley said she did not think that would become a possibility, then discussed healthcare policy – a rightwing rallying point in 2010, around the time of the passage of the Affordable Care Act, popularly known as Obamacare.

“I believe that … faith is being lost in Congress,” Haley said in the footage. “And as that happens, they’re gonna look at our governors for good conservative policy.

“I’m not just going to say no to Washington, I’m going to make sure we have solutions as to how we can keep them out and keep the states in control. When we do that, not only will it be me as the governor, I think it will be several states and governors that go and take our states back and keep Washington out of the way.

“So I’m one of those that’s an optimist by nature that doesn’t think it’s going to get to [secession] because I will fight as long as I need to to prove why DC needs to stay out of it.”

Her questioner said he was “positive too … positive it’s going to come to” secession.