NEW YORK (AP) — Presidential politics move fast. What we're watching heading into a new week on the 2020 campaign:

Days to general election: 78

Days to first debate: 43

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THE NARRATIVE

The first national political convention of the coronavirus era has arrived. For four consecutive nights beginning on Monday, Democrats from across the country will gather — in front of their computers, television screens and smart phones — for the all-virtual affair that will showcase the diversity of the modern-day Democratic Party and test Joe Biden's ability to energize his sprawling coalition.

President Donald Trump is working to step on the Democrats' convention — and prevent Biden from earning any convention polling bounce. The Republican president launches a campaign tour on Monday that features in-person stops in three swing states, including Wisconsin.

At the same time, coronavirus deaths continue to mount. With little guidance from the Trump administration, state and local governments are still struggling with a patchwork of inconsistent policies to combat the virus and revive their economies as the new school year begins.

Meanwhile, a new crisis is roiling. The U.S. Postal Service is struggling with significant delays that threaten to disenfranchise millions of Americans who prefer to vote by mail in the middle of a pandemic. As state election officials cry for help, Trump is questioning the integrity of voting by mail and casting doubt on the ability of the postal service to deliver ballots and of election officials to count them.

THE BIG QUESTIONS

How much excitement can a virtual convention generate?

National conventions traditionally mark a high point for presidential campaigns. There's nothing traditional about 2020.

Forced to abandon their in-person convention in Milwaukee because of the pandemic, Democrats begin their all-virtual affair on Monday night. There will be no physical gathering place, no cheering audience, no balloons. The program will consist of a series of online video addresses — roughly half of which will be prerecorded — that play out for two hours each night until Biden formally accepts the Democratic presidential nomination Thursday in a mostly empty Delaware ballroom.

While that may sound underwhelming, the last hour of the speaking program each night will be broadcast live on network television and feature the Democratic Party's elite: former President Barack Obama and first lady Michelle Obama, former President Bill Clinton and 2016 party nominee Hillary Clinton, Massachusetts Sen. Elizabeth Warren, Vermont Sen. Bernie Sanders and former South Bend, Indiana, Mayor Pete Buttigieg. Even a Republican former governor of Ohio, John Kasich, will speak on Biden's behalf.

There are no other moments in politics that offer campaigns the ability to deliver their carefully scripted message to millions of voters on prime-time television four days in a row. That's bound to energize some of Biden's coalition.

What is the Kamala Harris effect?

California Sen. Kamala Harris won the veepstakes five days ago, and we're just beginning to see her impact on the Biden campaign.

As we've noted before, the impact of running mates is often exaggerated. Still, the early reviews have been positive. Biden's campaign raised a staggering $48 million in the 48 hours after last week's announcement, people of color — in the African American and Indian communities — are excited, and Trump's campaign has struggled to identify a coherent message against her.

Trump's campaign surrogates have cast her as an extreme liberal, while Trump himself settled on a series of racist and sexist comments. The Republican president described Harris in recent days as a "madwoman" and claimed at a White House news conference to have "no idea" whether she was eligible to serve as vice president because her parents were immigrants. Born in California, she is eligible as set out in the Constitution.

Harris faces the largest test of her political career on Wednesday night when she makes history as the first woman of color to accept a major party's vice presidential nomination.

What is happening at the post office?

There may be no more important story in the United States right now than the health of the Postal Service, which will play a critical role delivering ballots this fall as tens of millions of Americans vote by mail to protect themselves from the pandemic.

There are legitimate concerns that the post office cannot do the job democracy requires. That's at least in part because of a series of changes the Trump administration implemented in recent weeks, including the inexplicable decision to remove mail sorting machines from key locations.

Democrats are contemplating a series of congressional hearings in the coming days, but with the Republican-led Senate on recess for the next month, it's unclear whether there is enough political will to fix the mounting crisis.

Can Trump step on the Democrats' convention?

Biden won't be in Wisconsin for the Democrats' convention as initially planned this week, but Trump will.

The Trump campaign has announced two in-person campaign appearances on Monday and a third on Tuesday as the Republican president works to undermine the opening days of the Democratic National Convention. He's scheduled to deliver remarks in Minnesota and Wisconsin on Monday before heading to Arizona on Tuesday.

Trump has proven to be a master of manipulating media coverage to ensure he's the center of attention, even if that attention isn't always positive. By being willing to travel to battleground states that Biden hasn't visited for months, Trump is ensuring that he'll be a significant part of the conversation on what may be the most important week of Biden's decades-long political career.

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THE FINAL THOUGHT

Rarely, if ever, has a political party highlighted as much political and racial diversity as Biden's Democratic Party will this week.

A woman of color will accept a major party's presidential nomination for the first time. Kasich, a Republican, will speak on Biden's behalf, as will a self-described democratic socialist, Sanders, and billionaire Michael Bloomberg.

Under normal circumstances, it might be difficult to keep such disparate political factions united. But Trump is proving to be the most important coalition builder Democrats have ever had.

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2020 Watch runs every Monday and provides a look at the week ahead in the 2020 election.