© Provided by INSIDER Vice President Joe Biden (R) and former Vice President Walter Mondale shake hands during an event honoring Mondale at The George Washington University in Washington October 20, 2015.
See more stories on Insider's business page. Mondale and his family believed that "death was imminent", Axios reports, but after his phone calls, he "perked up", Cosgrove said. It wasn't just Harris that Mondale chatted with over the weekend, Cosgrove said - he also spoke with Carter, President Biden, former President Bill Clinton, and Minnesota Gov. Tim Walz (D).
Mondale, whose nickname was Fritz, had a decades-long political career and was committed to his role of vice president when he served alongside former President Jimmy Carter.
Vice President Kamala Harris also paid tribute to Mondale and said she was able to speak with him recently.
"When President Obama asked me to consider being his Vice President, Fritz was my first call and trusted guide".
Biden also honored the work Mondale did as a senator.
Mondale served as a US Senator from Minnesota prior to working with Carter.
Mondale would go on to win the Democratic presidential nomination himself in 1984, and make history by naming a woman, US Rep. Geraldine A. Ferraro of NY, as his running mate before ultimately falling short to Reagan.
Mr Mondale was Jimmy Carter's running mate for his winning 1976 presidential bid and defeat four years later.
He served as United States ambassador to Japan from 1993 to 1996 in the administration of then president Bill Clinton, and worked to reduce the United States trade deficit with Japan.