The current POTUS exercised his civic duty Monday in Wilmington ... where he had spent the weekend before heading back to the Oval Office. Biden was seen waiting in line with other voters, chatting it up while they stood by to cast their vote 7 days early.

While Biden waited in line with fellow citizens to vote, he was surrounded by a score of Secret Service agents ... who've been catching quite a bit of heat this year following assassination attempts on Republican nominee Donald Trump.

Still, Biden appeared happy to be among the public ... smiling and shaking hands with voters and volunteers at the center, before and after voting.

It's safe to assume 46 cast his vote for his potential successor, Kamala Harris, who he tapped to replace him after exiting the race in July.

At the time, he offered Harris his "full support," noting selecting her to be his VP on the 2020 ticket was "the best decision [he's] made."

Since then, he's stayed off the campaign trail for the most part ... allowing Harris to have her moment in the spotlight.

Plenty of celebrities and prominent Democrats have voiced their support for Harris since she became the party's nominee ... including Beyoncé, Michelle and Barack Obama, Taylor Swift, John Legend, Jamie Lee Curtis, Billie Eilish, and Kerry Washington, among others.

Though, the race continues to be deadlocked, according to polls, between the VP and the former prez.