The Washington Nationals have invited Joe Biden to throw out of the first pitch of the 2021 season -- when they take on the New York Mets at home on April 1st.

And, right now, it seems they expect him to accept.

"We look forward to hosting President-Elect Biden on Opening Day of the 2021 season," the team said in a statement.

"We're excited to continue the long-standing tradition of sitting Presidents throwing out the first pitch at the home of the national pastime in our nation's capital."

Worth noting ... Donald Trump did NOT throw out a ceremonial first pitch at an MLB game during his presidency -- the ONLY president to skip the tradition since it began with William Taft in 1910.

Trump famously attended Game 5 of the 2019 World Series when the Nationals played the Houston Astros -- but he didn't throw out the first pitch.

As for Biden, he played a little baseball as a kid -- and threw out the first pitch for the Baltimore Orioles during Opening Day in 2009.

The pitch wasn't horrible (looking at YOU, Dr. Fauci) ... but it wasn't a perfect strike either.