Philadelphia (CNN) Former Vice President Joe Biden at an event Tuesday labeled President Donald Trump's response to Sen. John McCain's death as "almost un-American."

"I think you're going to see a significant change in the politics of the country, and I think lot of it had to do with the way in which the administration has treated people," Biden said at the University of Pennsylvania. "I think the nail that maybe have put in the coffin this time was the way in which the administration responded to John McCain's death, and the way it came across as being so nakedly ... almost un-American. It was just raw. It wasn't -- it's not who we are."

Trump was criticized for his reaction to McCain's passing, which initially was marked with only a tweet expressing sympathies to the McCain family. The flag atop the White House was initially lowered to half-staff following McCain's death on Saturday, but was re-raised Monday morning, even as many flags around Washington, including at the Capitol, remained lowered. Facing bipartisan pressure from lawmakers and veterans groups, Trump signed a proclamation that afternoon ordering flags nationwide to be flown at half-staff and issued a short laudatory statement.

"Despite our differences on policy and politics, I respect Senator John McCain's service to our country," Trump said in the statement, which also laid out the logistical details he approved for McCain's remembrance ceremonies.

Biden was among those to eulogize McCain, reminiscing about their decades-long friendship that stemmed from their time in the Senate.

Read More