Democrats will highlight the party's future leaders and turn to a political powerhouse from the past, former President Bill Clinton, to make the case for U.S. presidential candidate Joe Biden at their national convention on Tuesday.

Biden's wife, Jill Biden, one of his closest political advisers, will deliver the main speech for the second night of the Democratic National Convention, after an opening night that featured a scathing attack on President Donald Trump from former first lady Michelle Obama. 

Biden will be formally nominated on Tuesday. With the four-day convention largely virtual due to the coronavirus pandemic, delegates from around the country will cast votes remotely to confirm Biden, 77, as the Democratic nominee for the Nov. 3 election against the Republican Trump, 74.

The convention is being held amid worries about the safety of voting. Democrats have pushed mail-in ballots as an alternative but fear it could be hindered by cost cuts at the U.S. Postal Service that, under Louis DeJoy, a top Trump donor, have led to delays in mail service.

Rather than a single keynote speaker on Tuesday, the convention program will put the spotlight on 17 of the party's rising stars, including Stacey Abrams, the onetime Georgia gubernatorial nominee whom Biden considered for a running mate.

The night's theme is "Leadership Matters," organizers said.

In an effort to draw attention away from Biden, Trump will deliver a speech in Arizona, a hotly contested battleground state that can swing to either party and play a decisive role in the election.

Other Democratic speakers for the night include U.S. Representative Alexandria Ocasio-Cortez, a leading liberal figure; Sally Yates, the former acting U.S. attorney general who clashed with Trump during her brief tenure overseeing the Justice Department; former Secretary of State John Kerry; and Senate Minority Leader Chuck Schumer.

Democrats used Monday's opening program to demonstrate the broad coalition committed to defeating Trump in November.

Senator Bernie Sanders, the liberal who was Biden's chief rival for the nomination, urged his supporters to get behind the more moderate Biden despite their policy differences. Former Republican presidential candidate and Ohio Governor John Kasich argued that Trump poses a threat so dire that Republicans should consider voting for a Democrat in the race for the White House.

But Michelle Obama's impassioned speech drew the most attention. She decried Trump as the "wrong president" for a country reeling from the pandemic, an economic crash and a national reckoning on race relations.

Trump on Tuesday slammed the former first lady's remarks and reiterated his attacks on the previous administration of former President Barack Obama and Biden, Obama's vice president.

"Somebody please explain to @MichelleObama that Donald J. Trump would not be here, in the beautiful White House, if it weren’t for the job done by your husband, Barack Obama. Biden was merely an afterthought," he wrote on Twitter.

Trump also blasted the Obama administration's handling of the 2009 H1N1 swine flu outbreak even as his administration grapples with COVID-19. About 12,000 people died from H1N1, U.S. statistics show, compared to more than 170,000 U.S. deaths from the coronavirus pandemic still underway, according to a Reuters tally.

Joe Biden will deliver his acceptance speech on Thursday night. His vice presidential pick, Senator Kamala Harris, will headline Wednesday night's program along with former President Barack Obama, with whom Biden served as vice president.

The Republican National Convention, also largely virtual, takes place next week. Trump will give his acceptance speech at the White House, despite criticism he is politicizing the presidential residence. 

(Reporting by Joseph Ax; additional reporting by Katanga Johnson in Washington Editing by Colleen Jenkins, Howard Goller, Susan Heavey and Chizu Nomiyama) ((joseph.ax@thomsonreuters.com; 1-917-848-0813))