Former US Vice President Joe Biden speaks during a rally in Philadelphia May 18, 2019. Joe Biden on Saturday kicked off his running campaign for the 2020 presidential election in Philadelphia. (Photo: Xinhua)

Former US Vice President Joe Biden held a kick-off rally on Saturday for his 2020 presidential campaign in Philadelphia, state of Pennsylvania.

Addressing a crowd of supporters at Eakin's Oval near the Philadelphia Art Museum Saturday afternoon, Biden called for unity.

"Some of the really smart folks say Democrats don't want to hear about unity," Biden said in his remarks. "They say Democrats are so angry, and that the angrier your campaign will be, the better chance you have to win the Democratic nomination."

"Well, I don't believe it. I really don't. I believe Democrats want to unify this nation," he stressed.

Biden also took a shot at President Donald Trump.

"If the American people want a president to add to our division, to lead with a clenched fist, closed hand and a hard heart, to demonize the opponents and spew hatred - they don't need me. They've got President Donald Trump," the former vice president said. "I am running to offer our country - Democrats, Republicans and independents - a different path."

Those remarks came after Biden's campaign announced earlier this week that it will be based in Philadelphia.

Democrats and Republicans both view Pennsylvania, which has 20 electoral votes, as one of the most important battlegrounds in the 2020 race.

According to a poll released by Quinnipiac University this week, Biden leads Trump by 53 percent to 42 percent in Pennsylvania among registered voters.

Biden, 76, formally announced his bid for the Democratic nomination for US presidency in April.

Born in Scranton, Pennsylvania, Biden was the US vice president from 2009 to 2017. He represented state of Delaware in the Senate from 1973 to 2009, during which he was a longtime member and former chair of the Foreign Relations Committee.

After the vice presidency, he launched the Biden Center for Diplomacy and Global Engagement at the University of Pennsylvania in Philadelphia.