WASHINGTON, May 27 — Joe Biden attacked President Donald Trump as an "absolute fool” yesterday for belittling his election rival over recently wearing a mask, an issue that has become a partisan flashpoint during the coronavirus pandemic.

The Democratic Party’s presumptive 2020 presidential nominee had a series of choice words for the Republican incumbent, telling CNN in his first in-person interview since March that Trump has become increasingly erratic.

The interview, conducted in Biden’s garden and with social distancing measures in place, followed Memorial Day ceremonies Monday in which Biden wore a mask and Trump was bare-faced.

Trump retweeted a photograph of Biden and an accompanying message that mocked the former vice president for wearing a mask.

"He’s a fool, an absolute fool, to talk that way,” Biden said. "Every leading doc in the world is saying you should wear a mask when you’re in a crowd.”

Asked whether wearing a mask projected weakness or strength, Biden chose a different description.

"It presents and projects as leadership,” Biden said. "Presidents are supposed to lead, not engage in folly and be falsely masculine.”

Trump, who is 73, and Biden, 77, are both at high risk from Covid-19 because of their age.

Trump has refused to appear in public wearing a mask, and many of the Americans who are bare-faced at demonstrations calling for states to immediately reopen are supporters of the president.

"This macho stuff,” Biden added, has "cost people’s lives.”

An hour before the interview aired, Trump questioned why Biden would wear a mask outdoors, in "perfect conditions, perfect weather,” while he does not wear a mask in his home with his wife.

"So I thought it was very unusual that he had one on,” Trump said at the White House.

Trump has repeatedly mocked Biden as too old or gaffe-prone to wrest the White House from him in November’s election. 

Biden said he did not want to engage in name-calling with a president who is all-too-willing to do so, but he did not hesitate to point out Trump’s apparent anxiety over slippage in the polls.

"He seems to get more erratic, the more he feels like he’s behind the curve,” Biden said.

Yesterday Biden changed the profile image on his Twitter feed to a photograph of him wearing a black mask. — AFP