The political pundit hopped on the air following JB's surprise announcement Sunday morning to discuss the decision and the president's legacy ... and, check out the clip 'cause Van's personal connection to Biden's on display.

Jones compares Dems telling Biden to drop out with having to take a grandparents' keys away from them as they get older ... saying it's a fight the entire time, and leads to an emotional breakdown after.

Van's emotional breakdown seemed to be coming while he was talking ... admitting it hasn't been easy to comment on Biden in recent weeks -- calling this moment an especially human one and a difficult one for Joe and his family.

Jones repeats multiple times how much he loves Joe -- remember, Van served in the Obama administration -- and he tells young people watching that Biden's putting on a masterclass in patriotism by dropping out.

Van wasn't the only liberal on TV who couldn't hold back the emotion ... Delaware Senator Chris Coons also got emotional on-air, asking for a moment to compose himself.

Biden's announcement came as a shock to many -- including his own aides reportedly -- and, it's played out along party lines with Democrats thanking the president for his service and Republicans demanding he resign from the job.

Many liberals are already throwing their weight behind Vice President Kamala Harris ... though a few prominent party members -- like Barack Obama -- are waiting to see where the chips fall.