The political transformation just months ahead of the general election matchup with the Republican nominee, former President Donald Trump, has meant a rapid succession of changes for Democrats' 2024 calculus in general -- making the convention all the more noteworthy.

Here's what to watch on the first day:

Biden will speak Monday night

Up until a month ago, Biden had been expected to take the convention stage Thursday night, as is tradition for the party's nominee. Now, Biden will give a speech on the convention's opening night of Monday, as will his wife, first lady Jill Biden.

Biden is expected to use his keynote address as a symbolic handoff of his party to Harris, capping five decades in Democratic politics and pressing the case for what he says is the threat to the country if Trump returns to the White House.

Harris will be on hand to watch the president's speech. Signs in the arena will feature a regular Biden-ism: "Spread the faith." While Harris is expected to stick around through the week's events, ahead of her own speech, officials say Biden isn't planning to be in Chicago past his own appearance.

A focus 'for the people'

According to convention organizers, the theme for Monday's events is "For the People," a callback to the theme of Harris' 2020 presidential campaign, and a phrase she's been incorporating into her new one, starting with a fundraising email the very night Biden departed the race.

The phraseology hearkens to her 2019 launch, at which Harris -- a longtime prosecutor and California's first woman to serve as attorney general -- recalled introducing herself in court as "Kamala Harris, for the people," adding, "In my whole life I've only had one client, the people.'' Throughout that campaign, Harris returned to the phrase time and again, in speeches but also on signs and T-shirts, and as part of her principal campaign committee's official nomenclature.

At the convention's opening night, organizers note that speakers will aim to make the argument that, "while Donald Trump puts himself first, Democrats are fighting for the American people," something they say is reflected in Harris and her running mate, Minnesota Gov. Tim Walz.

In addition to the elected officials and party leaders, Democrats also plan to showcase "everyday Americans" and some performers during each night.

Protests are planned around town

Thousands of activists are expected to converge on Chicago, hoping to call attention to abortion rights, economic injustice and the war in Gaza. Demonstrations are expected every day of the convention and, while their agendas vary, many activists agree an immediate ceasefire in the Israel-Hamas war is the priority.

There have been months of preparation for the tens of thousands of activists expected in town. Chicago police have undergone training on constitutional policing, county courts say they are opening more space in anticipation of mass arrests and hospitals near the security zone are beefing up emergency preparedness.

Chicago Mayor Brandon Johnson, who is among the speakers expected to take the stage on the convention's opening night, said on ABC's "This Week" on Sunday that the city was prepared for the thousands of activists expected to participate in protests around the DNC.

"Our local police department has worked with the Secret Service as well as other local agencies to ensure a safe, peaceful yet vibrant, exciting convention," he said.

Trump's counterprogramming

As Democrats laud their top-of-the-ticket selectees, Trump and his running mate, Ohio Sen. JD Vance, have a full week of their own events stumping across battleground states. Like the Democrats -- and like at their own convention last month -- the Republicans are adding a theme to each day's events, with Monday intended to focus on the economy.

On Monday both Trump and Vance are in Pennsylvania, the Rust Belt battleground where both men have stumped in recent days. Each day of the DNC, Trump's allies will also be holding a news conference in Chicago, a prebuttal to what's expected from the stage at the United Center.

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Meg Kinnard can be reached at http://x.com/MegKinnardAP