"John McCain is a genuine hero — a man of valor whose sacrifices for his country are immeasurable. As he fights for [his] life, he deserves better — so much better," Biden said in the statement. "Given this White House's trail of disrespect toward John and others, this staffer is not the exception to the rule; she is the epitome of it."
Haspel testified before the Senate Intelligence Committee on Wednesday as she seeks to be confirmed as the head of the U.S. spy agency. She would be filling the position left open by Mike Pompeo, who became secretary of State after the firing of former Exxon Mobil CEO Rex Tillerson.
In a statement, the White House did not deny Sadler's comment.
"We respect Senator McCain's service to our nation and he and his family are in our prayers during this difficult time," the White House said.
The Trump administration skirted another opportunity to apologize to McCain or reprimand Sadler on Friday. "I'm not going to comment on an internal staff meeting," press secretary Sarah Huckabee Sanders told reporters at a White House briefing Friday afternoon.
McCain's family members also weighed in on Sadler's remark.
Meghan McCain, talk show co-host and the senator's daughter, criticized the White House on "The View" for not taking disciplinary action against Sadler.
"I don't understand what kind of environment you're working in when that would be acceptable and then you could come to work the next day and still have a job," McCain said Friday.
McCain's wife, Cindy, appeared to respond to Sadler in a Thursday tweet.
President Donald Trump has been a vocal critic of McCain. As a presidential candidate, Trump questioned McCain's service record in the Vietnam War, saying, "I like people who weren't captured."
McCain was a Navy pilot who spent years during the war in captivity, where he was beaten. Trump did not serve.
Trump's attacks continued even after winning the 2016 presidential election.
Trump repeatedly criticized McCain after the Arizona Republican famously cast the deciding thumbs-down vote tanking a GOP effort to overhaul health-care policy.
Biden's statement Friday suggested that Sadler's comment was of a piece with the "trail of disrespect" established by the Trump administration.
"Given this White House's trail of disrespect toward John and others, this staffer is not the exception to the rule; she is the epitome of it," Biden said.
He added: "Our children learn from our example. The lingering question is whose example will it be. I am certain it will be John's."