Tonight, Trump debates the man he's spent months taunting as 'Sleepy Joe'

We're about to find out whether a central message of the Trump campaign withstands the scrutiny of 90 minutes in the glare of television lights.

U.S. President Donald Trump and his rival Joe Biden are about to go head-to-head in the first and possibly most important of three televised debates, starting at 9 p.m. ET.

CBC News will have special live America Votes coverage of the presidential debate, with several options for viewers and listeners.

The debate will be broadcast at 9 p.m. ET on CBC News Network, which can alsobe streamed at CBCNews.ca and through the CBC Gem app. Pre-debate coverage hosted by Carole MacNeilin Toronto and Lyndsay Duncombe in Washington starts at 7 p.m.

CBC Radio One listeners can tune in between 9 p.m. and 11 p.m. for coverage hosted by Susan Bonner and Piya Chattopadhyay.

Which gives tens of millions a chance to judge for themselves a basic premise of the president's campaign argument: that his opponent is sliding into senility and too mentally feeble to lead an administration.

It's been the recurring theme of video clips churned out by the president's social media operation showing Biden verbal gaffes some aredeceptively edited, some arenot,and they collectively pushthe notion that he'd be a mere figurehead in his own administration.

The president has, approximately 120 times on Twitter, referred to his opponent as "Sleepy Joe." Trump's son repeated the message Monday.

"Joe Biden can't remember where he is 50 per cent of the time. He forgets the office he's running for," Donald Trump Jr. told Fox News.

He is the "most inept" candidate "in terms of speaking, in terms of ability."

WATCH | CBC's Katie Simpson is in Cleveland for tonight's debate:

CBC's Katie Simpson previews tonight's debate

4 years ago

Duration 2:01

What to expect in the 1st debate between U.S. President Donald Trump and Democratic presidential candidate Joe Biden

This first debate could be Trump's best chance to turn things around as he consistently trails in national pollswhile remaining close in several key swing states.

By the time of the later debates, on Oct. 15 and 22, more voter opinions will have hardened. Fewer viewers will, if history is any guide, tune into those later ones; and more advance ballots will already have been cast.

That's why some campaign veterans have been claiming for many weeks that Sept. 29 was the date they were watching.

The topics

The debate in Cleveland will be moderated by Chris Wallace, a well-regarded, straight-shooting Fox News interviewer.

The topics, as chosen by Wallace, are:

• Trump's and Biden's records. Expect Trump to focus heavily on the booming pre-COVID economy. Pro-Biden groups are arguing that neither the economy nor manufacturing jobs grew faster under Trump. Count on Biden bringing up a New York Times investigation into Trump's taxes.
• The Supreme Court. Trump has reason to hope the upcoming nomination battle over Amy Coney Barrett energizes conservative-leaning voters. Expect Biden to turn this into a conversation about health care. The main Democratic talking point now is to link this fight to the social safety net. Coney Barrett has criticized the so-called Obamacare law, which the court will examine one week after the election. Millions of people gained health coverage under this law.
• COVID-19. The health care discussion will spill over here. Trump will likely argue that he limited travel at a time Democrats including Biden opposed it. Biden will point to the high U.S. death rate; failures in testing; and Trump's own misleading rhetoric about the virus. Biden's platform also calls COVID-19 a wakeup call that exposed other failures of the U.S. safety net.
• The economy. Trump has repeatedly hammered Biden as too soft on foreign trading partners, and for supporting China's entry into the World Trade Organization, which coincided with a collapse in manufacturing employment. If trade gets discussed in detail, Biden may defend himself by mentioning his own Buy American policies.
• Race and violence in cities. Trump's main election message since the summer is that radical leftists have overrun the streets, and Biden is too mentally weak to stand up to them. He also accuses Biden of being willing to defund the police which Biden has repeatedly said he wouldn't do. Bidenaccuses Trump of intentionally fomenting anger.
• The integrity of the election. It's a debate topic that would have been almost unthinkable in the pre-Trump era. The president is insisting, repeatedly, as he did in 2016and in 2012, that the election is rigged against his party. Trump won't commit to leaving office after the election.

Now, after spending months describing his opponent as cognitively deficient, Trump is pre-emptivelybrushing off any expectations-defyingperformance from Biden by making a bizarreaccusation that he's taking performance-enhancing drugs. Hemade the same claimin 2016againstHillary Clinton.

Some former Obama aides say incumbent presidents havegood reason to fear a first televised debate: They've typically fared poorlybecause, when it comes to debating, presidents are out of practiceand tend to get overly defensive about their record.

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Veterans of the Obama campaign describe moments of panic and sleeplessness after Obama was clobbered by Republican Mitt Romney in their first 2012 encounter.

Why some have circled this date

One former senior Obama communications aide, David Axelrod, said he had been worrying about that debate for months and had it circled in red on his calendar.

He said weeks ago that Sept. 29 is the one date he'd circle on the calendar this time as potentially having the biggest impact.

He was speaking on a podcast hosted by Obama's former campaign manager, David Plouffe, who concurred: "Circle Sept. 29. That may be the most important date in the rest of the campaign."

This most-watched event of the race gives Trump a rare opportunity to shift the campaign's trajectory. In 2016 the first presidential debate drew an estimated 84 million viewers, nearly triple the audience for the conventions.

Biden has been considered the front-runner for many months.

According to CBC's Presidential Poll Tracker, Biden is leading by at least five percentage points in enough states to win a narrow victory even if all of the closer states end up going to the Republican incumbent.

That said, political science research on debates say they rarely make a difference with voters. Several researchers have drawn that conclusion.

In fact, there's been an opposite correlation between winning the first debate and winning the election.

Only three times in 11 elections, dating back to the first U.S. televised debate in 1960, did the candidate deemed to have won the first debate by respondents in a Gallup pollalso wind up winning the election.

A rare debate that might have made a difference: 1980.

Democrats were in trouble. Yet doubts persisted about Ronald Reagan, whom they cast as a trigger-happy extremist who might cause World War Three.

The old actor commanded the stagewith geniality and good humour. "And that was it," Axelrod said in the podcast. "The bottom dropped out"on President Jimmy Carter.