Of course Obama knew and this same comment pointing out the slow endorsement has been made before, especially during the primaries where Obama failed to endorse Joe.

There has been a lot said in the past about Biden's corruption, it was an open secret but we never had solid proof before.

Obama was worried about his "legacy", which is already in tatters but it is quite clear with Biden and Clinton that Obama's was the most corrupt administration of all time. Meanwhile the left try to claim it had no scandals, dumb bastards.