Former President Barack Obama and Michelle Obama sat down for their first joint TV interview in a decade ahead of his presidential library opening this week. 

The couple appeared on Good Morning America and spoke with Robin Roberts inside the center based in Chicago.

The 225-foot tall library dubbed the 'Obamalisk' is due to open with live performances, activities, food and art on Friday and is several hundred million dollars over its initial $300 million budget.

Roberts quizzed Obama over what he was most proud of after having left the White House, with the former commander-in-chief touting Obamacare as his biggest achievement.

He said: 'There is a lot of stuff I am proud of, for all of the resistance from our political opposition, the Affordable Care Act has now helped 50-60 million people.

'It continues to help even though the current congress has tried to weaken it and taken away some of the subsidies.'

Obama also said he was most proud of the 'tone we set', adding: 'I'm very proud of the message we sent to the country that we're representing everybody.' 

When asked what he would do differently, he gave a candid response in believing he felt he was making a 'mistake a day' while in office.

He continued: 'The thing that we were good at and allowed me to sleep at night and get up and go back at it, was I always felt when we were making decisions we were making decisions with the American people in mind.'

Obama was also questioned about President Trump's announcement of a deal with Iran that would see the Strait of Hormuz reopened. 

He said he was doubtful that any deal would be any different from a deal he struck with the nation in 2015. 

He said: 'It is doubtful that any agreement that arises is going to be significantly different or a significant improvement from the deal that we had in the first place and had worked for, for a long stretch of time before we, the United States, pulled out of it.

'So, I'm hopeful that bombing stops and ordinary people are no longer suffering as a consequence of the war.

'In retrospect it's a reminder that on a lot of different foreign policy problems, the notion that we can just bully our way or bomb our way to solutions may sometimes seem appealing. 

'The fact of the matter is that taking the time to explore diplomacy and exhaust the possibilities of coming up with deals that don't solve 100% of the problem but solve 80%, 90% of the problem while avoiding the necessity of going to war.

'You'd think we would've learned that lesson by now. But it seems like every so often we have to relearn that lesson again.'

Details of that tentative deal that Trump has struck with Iran remains under wraps, with officials so far offering contradictory interpretations of what is in it. 

Bruce Springsteen, Stevie Wonder, John Legend and Christina Aguilera are just some of the stars performing at the event on Friday. 

A delay in its opening and the rise in cost was pinned on the pandemic, but an ongoing spat with contractors has been public for months.

This is a breaking news story.