Biden fielded the first question from moderator Jake Tapper, who asked him what his message was to Americans who feel worse off financially under his administration than they did under Trump.

Biden claimed he was handed an economy in "free fall." He touted his record on job creation and lowering prescription drug prices and other household costs.

Trump, in turn, claimed he he had "the greatest economy in the history of our country" and that inflation is "absolutely killing us."

Biden and Trump are now at the lecterns. The two entered from different sides of the stage and did not shake hands.

ABC News Senior Congressional Correspondent Rachel Scott reported that Melania Trump will not be at the debate.

The former first lady has made few appearances on the campaign trail as her husband seeks another term.

Biden posted a photo on x taking a shot at Trump's allegations that he's taking performance-enhancing substances for the debate.

The president is seen holding a can of water with the "Dark Brandon" meme image claiming to be "Dark Brandon's secret sauce." The can, which will go on sale on the Biden campaign's site next month, has a statement in bold letters "Get real, Jack. It's just water."

"I don't know what they've got in these performance enhancers, but I'm feeling pretty jacked up. Try it yourselves, folks. See you in a bit," the X post said.

Heading into tonight's event, Biden and Trump are locked in a close contest. 538's presidential election forecast rates the race as a dead heat, with both Biden and Trump having about a 1 in 2 shot of winning the election. This falls in line with our national polling average, which has the two candidates just about tied at 41%, with Kennedy polling at 9%.

But as readers know, U.S. presidential elections aren't decided by the national popular vote. Instead, they're decided by the Electoral College, where the results in individual states determine who wins each state's electoral votes, with a majority of 270 out of 538 in total necessary to claim victory. Currently, the forecast shows an extremely tight race in each of the most pivotal states.

For instance, Biden's path to victory may rest primarily on winning the Frost Belt battlegrounds of Michigan, Pennsylvania and Wisconsin that he carried in 2020. While the forecast shows him with small leads in each of those states, Biden's advantage is well inside the range of potential outcomes, meaning Trump could easily carry them once we get to November. Meanwhile, Trump holds a narrow edge in the Sun Belt swing states of Arizona, Georgia, Nevada and North Carolina, but similarly his leads are far from secure.

Still, with nearly four months to go until Election Day, there's a great deal of uncertainty around where public opinion will stand when voters cast their ballots. 538's forecast utilizes a combination of polling information and campaign fundamentals, such as the economic situation and each state's partisan leanings. Together, those indicators show a toss-up race that could go in either direction.

Now, tonight's debate could move the contest: Historically, the margin in presidential races has shifted by an average of about 2 points in the two weeks following the first general election debate in cycles dating back to 1976. In what could be bad news for Biden, that movement has more often than not gone against the incumbent president or party. Yet we're still sailing in uncharted waters. After all, this election involves both a sitting and former president, an unprecedented matchup in modern times. The debate is history-making, too: It's nearly three months earlier than any past general election face-off.

-538's Geoffrey Skelley