President Biden on Sunday held a press conference in Rome to conclude a two-day meeting with G20 leaders before heading to a United Nations climate summit in Glasgow, Scotland.

Biden, who showed up more than 20 minutes late to the briefing, began by apologizing for his tardiness. "I apologize to keep you waiting," he said. "We were playing with elevators. Long story, anyway."

U.S. President Joe Biden arrives for a press conference at the La Nuvola conference center for the G20 summit in Rome, Sunday, Oct. 31, 2021. Leaders of the world's biggest economies made a compromise commitment Sunday to reach carbon neutrality "by or around mid-century" as they wrapped up a two-day summit that was laying the groundwork for the U.N. climate conference in Glasgow, Scotland. (AP Photo/Andrew Medichini)

The president went on to speak about the issues that G20 leaders addressed during the summit, which focused primarily on climate issues, but also featured "broad support" for a landmark deal to establish a 15% global minimum corporate tax.

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The G20 leaders made a vague commitment during their meeting to seek carbon neutrality "by or around mid-century," which some claimed is not enough to stymie the threats of climate change.

The president called out China and Russia, saying they "didn't show up in terms of any commitments to deal with climate change. And there's a reason why people should be disappointed that I found it disappointing myself."

The United States and the European Union set 2050 as their goal to achieve net-zero emissions. China, Russia and Saudi Arabia, whose leaders did not attend the G20 summit, have set 2060 as the year they hope to achieve the same. China leads the emerging economies whose emissions are increasing along with their economic growth.

U.S. President Joe Biden speaks during a press conference at the La Nuvola conference center for the G20 summit in Rome, Sunday, Oct. 31, 2021. Leaders of the world's biggest economies made a compromise commitment Sunday to reach carbon neutrality "by or around mid-century" as they wrapped up a two-day summit that was laying the groundwork for the U.N. climate conference in Glasgow, Scotland. (AP Photo/Andrew Medichini)

Biden also brushed off his plummeting poll numbers at home, where 54% of voters disapprove of his performance and 71% believe the country is headed in the wrong direction, according to an NBC News poll released Sunday.

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"Look, the polls are going to go up and down and up and down. They were high early, then they got medium, then went back up and now they're low," said Biden. Saying such has happened to every president, Biden said, "That's not why I ran. I didn't run to determine how well I'm going to do in the polls. I ran to make sure that I followed through on what I said I would do as president of the United States."

President Joe Biden walks off the stage after speaking during a news conference at the conclusion of the G20 leaders summit, Sunday, Oct. 31, 2021, in Rome. (AP Photo/Evan Vucci)

Biden concluded the press conference by talking about his Roman Catholic faith and his meeting with Pope Francis. After taking a question about calls from some U.S. bishops that he should be denied Communion because of his abortion views, Biden said the issue was "personal," but also went on to laud the pope for supporting him when his son Beau died.

While he was leaving the presser, Fox News White House correspondent Peter Doocy shouted a question, asking, "Mr. President, is true we're going to give $450,000 to border crossers who are separated?"

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Biden did not respond to the question, instead looking away from the camera and scratching his forehead.

From Rome, Biden will go to Scotland for the 26th Conference of the Parties to the U.N. Framework Convention on Climate Change (COP26).

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The Associated Press contributed to this report.