Former Vice President Joe Biden Joe BidenPelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Hillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Fox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio MORE could "absolutely" muster the energy for a 2020 presidential bid, his brother said in an interview released Wednesday.

"Absolutely. Absolutely," Frank Biden told SiriusXM host Michael Smerconish when asked if the former vice president could launch a White House campaign in 2020. "Why anyone would think otherwise, I don't know."

Speculation swirled in the fall of 2015 that then-Vice President Biden could enter the 2016 presidential race, launching a challenge to former Secretary of State Hillary Clinton Hillary Diane Rodham ClintonFox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio Trump, Biden court Black business owners in final election sprint The power of incumbency: How Trump is using the Oval Office to win reelection MORE, the Democratic Party's eventual nominee.

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But Biden ultimately declined to run, saying that he and his family were still grieving the death of his elder son Beau, who died of brain cancer earlier that year, and that the window for him to launch a White House bid had passed.

"You have to wonder how my lovely brother can put his feet on the floor every morning with the losses he's endured," Frank Biden said Wednesday.

"If you look at it objectively, Joe is one of the few people in the United States that commands respect from the right and the left, based on the fact that you may not like what Joe says, but you can take to the bank whatever he says is true."

Since leaving office in January, however, rumors of a 2020 presidential run for Joe Biden have reemerged. The former vice president created a political action committee earlier this month geared toward electing Democrats to office.