By Dan Merica and Eric Bradner, CNN

(CNN) -- The fourth and final night of the Democratic National Convention will culminate with Joe Biden giving the speech he has been hoping to deliver for decades when he accepts his party's presidential nomination.

A nominee's acceptance speech is a critical moment of any presidential campaign. But this speech may carry more weight, given most campaigning has been halted by the coronavirus. That lack of regular contact with the Biden himself puts even more pressure on a primetime address that could shape the way voters see both the Democratic Party and Biden's candidacy.

Viewers will watch what Biden says -- especially how he frames his campaign against President Donald Trump before a national audience -- with Republicans set to spend much of the following week at the Republican National Convention casting the former vice president as old and out-of-touch.

But don't expect Biden's speech to be centered on Trump, a senior adviser told CNN. Instead the former vice president, while sharply criticizing the President, will seek to look beyond the Trump presidency and strike a more aspirational and optimistic tone.

Biden will be far from alone in attacking Trump and defending Democrats, though, joined by three women he vetted to be vice president over the last two months and four Democrats who ran against him in the Democratic primary.

The first three nights of the convention have been a successful, albeit unconventional, affair. But event organizers know that the final night -- and Biden's speech -- will largely shape the way voters see the success or failure of the four-night event.

Here is what to watch for on the final night of the Democratic National Convention:

What will Biden say?

The first three nights of the Democratic convention have cast the 2020 race as one of character -- and that's the theme Biden is likely to lean into heavily on Thursday night.

He has long said the presidential race is a "battle for the soul of our nation" -- a slogan he plastered on the side of his campaign bus during the Democratic primary. He's said he decided to run for president after watching Trump call refer to white supremacists and anti-racist counter protesters in Charlottesville, Virginia, as having "very fine people on both sides."

Will Biden offer a new, sharper line of attack against Trump's character? Or will he stick to his typical themes -- ultimately keeping the race on its current trajectory as a referendum on the incumbent?

A senior adviser told CNN on Wednesday night that Biden sees this moment "as bigger than President Trump" and "an opportunity to make his affirmative case to America."

The convention so far, from its opening with a moderator asking average Americans how they are doing through Jill Biden's speech from a closed classroom Tuesday night, has shown that Democrats believe the coronavirus pandemic, and Trump's handling of it, are all that really matters right now. Biden is likely to seek to connect Trump's actions during the pandemic to his broader argument against the President's character.

Biden's moment

Biden has sought the Democratic presidential nomination for nearly half his life.

He ran for president three times — in 1988, when a plagiarism scandal effectively ended his hopes; in 2008, when he gained no real traction as then-Sen. Barack Obama ignited a movement; and finally, this year, when he said he felt the "soul of the nation" was at stake.

Finally, in a year in which his old-school political instincts that drive him toward compromise appear to meet an unprecedented moment, he'll deliver the speech he has spent decades seeking to give.

One-time opponents to tout Biden

They ran against Joe Biden. Now they speak for him.

Four of Biden's former primary opponents -- New Jersey Sen. Cory Booker, former South Bend, Indiana, Mayor Pete Buttigieg, former New York Mayor Michael Bloomberg and businessman Andrew Yang -- will tell Democrats about the Joe Biden they got to know on the campaign trail and why they believe he should be president.

Most Democrats still have vivid memories of the unwieldy and crowded Democratic primary. So, having multiple candidates who ran against Biden now tout his candidacy could prove powerful with the Democratic base. Booker, Buttigieg, Bloomberg and Yang join former candidates like Sen. Elizabeth Warren, Sen. Bernie Sanders and vice presidential nominee Kamala Harris in addressing the convention.

Buttigieg's speech, according to an aide, will continue with the message of belonging that anchored the former South Bend mayor's campaign but "tie that to how President Joe Biden will bring people together to overcome our greatest challenges."

Yang, whose upstart presidential campaign was centered on calls for a Universal Basic Income, will both offer a nod to the untraditional base that propelled him during the primary and argue why voters who may have never considered backing Biden or Harris should get behind them, lauding the duo as people who "understand the problems we face" and "want the best for our country," according to prepared remarks.

Booker, as part of a taped conversation with California Gov. Gavin Newsom, will discuss "why he still feels a sense of hope in these difficult and dark times and issue a call to action that this moment demands more from all of us to join together," said a Booker aide.

And Bloomberg, a former Republican whose selection to speak at the convention drew condemnation from liberal Democrats, plans to discuss "why we have the best candidates to meet today's challenges and get big things done," his political organization said in an email to supporters.

Biden gets a boost from once prospective VP candidates

Biden interviewed 11 women to be his running mate. On Thursday, three of those finalists -- Wisconsin Sen. Tammy Baldwin, Atlanta Mayor Keisha Lance Bottoms and Illinois Sen. Tammy Duckworth -- will address the convention on Biden's behalf.

Their message will exemplify the diversity of the women Biden vetted to be his running mate and provide the former vice president validators on topics ranging from health care to support for military families.

Baldwin, an aide said, "will discuss the choices before voters and what kind of America we want to be, focusing particularly on her own health care story." The Wisconsin senator, a groundbreaker as the first LGBTQ person elected to the Senate in 2012, was vetted in large part because of her legislative bona fides and the fact that she came from a key swing state.

"What kind of country do we want to be," Baldwin will ask, according to prepared remarks provided to CNN. "Where 'We the People' means just certain people or one where 'We The People' means all the people?"

Duckworth, another finalist to be Biden's running mate, will note how the Bidens have deep military ties -- most notably through their late son Beau Biden, who died of brain cancer in 2015 -- and argue that Biden "will look out for veterans and military families unlike Donald Trump," an aide said. Duckworth is a US Army veteran who lost both of her legs while serving in Iraq.