President Joe Biden signed an executive order at the White House Tuesday expanding access to the Affordable Care Act, and former President Barack Obama was there for his first visit back since leaving office in 2017.

The executive order Biden signed expands coverage for 200,000 uninsured people who pay more than 10% of their income for coverage, according to the White House, and it will lower premiums for nearly 1 million others.

Biden was introduced at the signing by Obama, who called him “Vice President Biden” before quickly correcting himself. “That was a joke,” Obama said. “That was all set up.”

Biden then introduced himself by saying, “My name’s Joe Biden and I’m Barack Obama’s vice president and Jill Biden’s husband.”

Obama’s visit was his first back to the White House since the morning of Jan. 20, 2017, the day of former President Donald Trump’s inauguration.

During his remarks, Biden spoke about Republican attempts to repeal the Affordable Care Act and said if they had their way, 100 million Americans with preexisting conditions could be denied health care coverage.

“They haven’t stopped for one second,” Biden said of Republicans. “Sabotage from the previous administration, over 70 attempts to repeal the law by Republicans in Congress.”

The Affordable Care Act, or ACA, was signed into law by Obama in 2010 and is also known as “Obamacare.” A 2020 Gallup poll found 55% of Americans approve of the ACA, a record high, and record 31 million Americans have health coverage through the ACA as of June 2021, according to the Department of Health and Human Services.

Though a majority of Americans back the law, it’s polarizing. The 2020 Gallup poll found that while 94% of Democrats supported the ACA, just 13% of Republicans also supported it.

Trump has said he wants the Affordable Care Act terminated, and during his administration, the law was undermined through efforts including reducing the enrollment period, cutting subsidies for insurance companies and promoting state waivers, according to the Brookings Institution.

Biden said he wants the ACA expanded.

“Instead of destroying the Affordable Care Act, let’s keep building on it,” Biden said. “Let’s extend it.”