CHICAGO, United States (AFP) — Former US Vice President Joe Biden strongly criticised President Trump Wednesday, and predicted an emboldened and determined Russia would once again meddle in an American election.

In public comments at the Chicago Council on Global Affairs, Biden — the target of speculation of a possible presidential run in 2020 — thoroughly rebuked Trump and his policies.

“We’ve got to stop this tweeting… it’s childish,” he said. “It’s time to grow up and act like a world leader.”

Biden, Barack Obama’s former vice president, has made international politics a key area of focus since leaving office.

He accused Russian President Vladimir Putin of seeking to mask problems at home by “stoking discord” in European countries and the United States.

“Russia’s attack on our election was not an isolated incident,” Biden said.

“The efforts to spew disinformation infiltrate our networks, corrupt our political institutions, they continue. And, we’ll surely see this kick into full gear as we head into another critical Congressional election cycle in 2018.”

Biden also criticised Trump for not taking a more forceful stand against Russian meddling, and said his international policies in general — such as withdrawing from the Trans-Pacific Partnership — threatened America’s alliances.

A former senator from Delaware with working-class roots, Biden has long been seen as a champion of the same demographic that favoured Trump in the 2016 election: white, working-class people who are struggling economically.

“These people aren’t prejudiced. They are realistic. And they’ve become targets to charlatans,” Biden said.