Atlanta. President Joe Biden reassured voters that, at 81, he’s capable of guiding the US through a range of challenges when moderators questioned him and his rival Donald Trump on their ability to be president at their age during the first general election debate of the 2024 season on Thursday evening in Atlanta.

Biden, 81, answering with the hoarse voice he’s had all night, launched on a litany of policy achievements and noted that Trump is only “three years younger.”

Biden also used the answer to slap at Trump for bad-mouthing the U.S. “The idea that we are some kind of failing country? I’ve never heard a president talk like that before,” Biden said.

In his retort, Trump bragged about his golf game and said he’s in as good a shape as he was 25 years ago and perhaps “even a little bit lighter.”

Almost 45 minutes into the debate, Biden finally referenced former President Trump’s recent felony conviction in New York.

During a discussion about the Jan. 6, 2021, insurrection, Biden said: “The only person on this stage that’s a convicted felon is the man I’m looking at right now,” referring to Trump.

Trump then sought to pivot from his own legal troubles by referring to Biden’s son, Hunter, as a “convicted felon.”

He was referencing the younger Biden’s felony conviction this month on three firearms charges. 

Early into the debate, questions are turning to Jan. 6, 2021, when supporters of then-President Trump stormed the US Capitol during the certification of the Electoral College vote count.

Trump was asked by host Jake Tapper whether he violated his oath to protect and defend the Constitution.

Trump quickly pivoted to immigration and taxes. Pressed on his role, he said he encouraged people to act “peacefully and patriotically,” then attacked former House Speaker Nancy Pelosi.

The rioters on Jan. 6 engaged in hand-to-hand combat with police and used makeshift weapons, including flagpoles, a table leg, hockey stick and crutch, to attack officers. Police officers were bruised and bloodied as they were dragged into the crowd and beaten. One officer was crushed in a doorframe and another suffered a heart attack after a rioter pressed a stun gun against his neck and repeatedly shocked him.

More than 1,400 people have been charged with federal offenses stemming from the riot. Of those, more than 850 have guilty people have pleaded guilty to crimes, including seditious conspiracy and assaulting police officers. About 200 others have been convicted at trial.

Trump falsely claimed that Pelosi “turned down” his offer to send “10,000 soldiers or National Guard” to the Capitol during the Jan. 6 insurrection.

Pelosi does not direct the National Guard. Further, as the Capitol came under attack, she and then-Senate Majority leader Mitch McConnell called for military assistance, including from the National Guard.

The Capitol Police Board decides on whether to call National Guard troops to the Capitol. It is made up of the House Sergeant at Arms, the Senate Sergeant at Arms and the Architect of the Capitol. The board decided not to call the guard ahead of the insurrection but did eventually request assistance after the rioting had already begun, and the troops arrived several hours later.

There is no evidence that either Pelosi or McConnell directed the security officials not to call the guard beforehand.

At two different moments in the debate, Biden said either 159 or 158 presidential historians voted Trump the worst president in US history.

He admitted he didn’t have the exact number, and he was right, though he wasn’t far off.

The survey in question, a project from professors at the University of Houston and Coastal Carolina University, included 154 usable responses, from 525 respondents invited to participate.

Both candidates also talked about climate change, which Biden has called an existential crisis and a top priority of his presidency.

Trump, after initially declining to answer on climate, said he wants “absolutely immaculate, clean water and I want absolutely clean air.’’

He said that during his administration, “we were using all forms of energy, all forms, everything’’ and claimed he “had the best environmental numbers ever.’’

It was unclear what he was referring to.

Biden called climate change the greatest threat to humanity, adding that Trump “didn’t do a darn thing about it.’’

Biden cited the 2022 passage of the Inflation Reduction Act, which is authorizes billions for clean energy. Biden called it the most significant climate legislation ever passed.

Thursday’s debate in Atlanta marks at least a couple of firsts -- never before have two White House contenders faced off at such advanced ages, and never before has CNN hosted a general election presidential debate.