Former U.S. President Barack Obama returns to the national stage on Tuesday night to boost his longtime Democratic ally Kamala Harris in her 11th-hour presidential bid against Republican Donald Trump, Paralel.Az reports citing Reuters.

America's first Black president, Obama has thrown his considerable political capital behind Harris as she seeks to make history herself on Nov. 5 as the first woman and first Black and South Asian person to be elected U.S. president.

Obama will be preceded by his wife, Michelle, who tops Democrats' wish list as a future president.

DNC festivities kicked off for a second day on Tuesday at Chicago's United Center but were marred by long delays to get into the security perimeter, leaving seats empty when it was time for a roll call of states' delegates.

Harris joined virtually from a campaign rally in Milwaukee. Delegates in Chicago raised signs saying “FREEDOM” that mirrored those raised by supporters at her Wisconsin rally.

Harris and her vice presidential pick, Minnesota Governor Tim Walz, took to the Milwaukee stage in the same venue as last month's Republican National Convention, where Trump formally received his party's nod.

In her speech, Harris criticized Trump for saying he had no regrets about the U.S. Supreme Court's 2022 ruling that overturned the 1973 Roe v. Wade decision that had recognized women's constitutional right to abortion. Three Trump-appointed justices joined a 6-3 majority on the high court.

"I do believe, you know, bad behavior should result in a consequence. Well we will make sure he does face a consequence and that will be at the ballot box in November," Harris said.

Democrats see abortion rights as a winning issue in this campaign and Harris had led the charge as vice president.

The roll call at the DNC turned out to be a surprise star-studded event - rapper Lil Jon performed his hit "Turn Down For What" alongside the Georgia delegation, film director Spike Lee appeared with New York’s delegation and actor Sean Astin of “Rudy” fame spoke for Indiana.