Vice President Joe Biden also declined to speculate on whether he could have run a stronger campaign that Hillary Clinton. | Getty Biden refuses to rule out 2020 run

Vice President Joe Biden has once again refused to rule out running for president in 2020.

"Four years is a lifetime in American politics," Biden said in a pretaped interview with host Jake Tapper that aired Sunday on CNN's "State of the Union." "And I think nominees are determined by their parties based mostly on what skill set is most needed at that time. And who knows where we're going to be two years from now, when people are really starting to look seriously at what they're going to do."


Biden also declined to speculate on whether he could have run a stronger campaign than Hillary Clinton.

"Oh, I don't know," Biden said. "They probably would have eaten me alive."

But he hinted that Democrats should have done more to reach out to white men.

"There's this sort of sense that's grown up in the Democratic Party that somehow these folks are …," Biden said, trailing off. "These are good people, man! These aren't racists. These aren't sexists."

Asked about President-elect Donald Trump's decision to tap Sen. Jeff Sessions (R-Ala.) as his attorney general, Biden acknowledged his former Senate colleague wouldn't have been his choice for the post. Biden led the fight against Sessions in the Senate when Ronald Reagan tried to appoint him as a federal judge in the 1980s. But Biden suggested he wouldn't be inclined to try to block Sessions this time around if he were still in the Senate.

"People learn," Biden said. "People change. And my general rule is the president gets to choose who he wants or she wants for their Cabinet members," unless there's evidence the nominee doesn't intend to enforce the law.

Oklahoma Attorney General Scott Pruitt, Trump's pick to head the Environmental Protection Agency, might meet that test, Biden said.

"If he's going not to enforce Clean Air and Clean Water acts in the name of jobs, then that's not a guy you vote for," Biden said.

Despite his criticisms of the party's message in 2016, Biden said he was encouraged about Democrats' prospects in two years in the midterm elections, when voters will be grading Republicans on their performance.

"I think 2018's going to be a very good year for the Democrats," Biden said.

In the short term, Biden said he plans to continue his work on cancer research, perhaps at a university.

"Is there going to be a Biden Center somewhere?" Tapper asked.

"Yeah, I think so," Biden said. "I think I'm going to be able to be in a position — I'm talking to some universities who want me to become engaged."