Former Secretary of State Hillary Clinton released audio of her recounting a conversation she had with her husband, Bill Clinton, when she decided to support Vice President Kamala Harris as her party's nominee. 

"After I got off the phone with the vice president, I looked at Bill with a huge smile and said, ‘This is exciting!'" Clinton said in audio recorded for the epilogue of her upcoming book, "Something Lost, Something Gained." 

The audio was first shared with MSNBC's "Morning Joe," one of several staunchly pro-Biden-Harris shows on the liberal network.

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Clinton, the Democratic Party's nominee in 2016, endorsed Harris for president after initially supporting President Biden. She has also called on Harris to break the "glass ceiling" and become the country's first female president, according to BBC. 

"I felt promise, I felt possibility. It was exhilarating!" Clinton said of speaking with Harris. 

"When I imagine Kamala standing before the Capitol next January, taking the oath of office as our first woman president, my heart leaps." 

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"After hard years of division, it will prove that our best days are still ahead and that we are making progress on our long journey toward a more perfect union," she continued. "And it will make such a difference in the lives of hard-working people everywhere." 

Clinton also praised Biden for his service. 

"Democrats have lost our standard-bearer," Clinton said. "We will miss Joe Biden's steady leadership, deep empathy, and fighting spirit. He is a wise and decent man who served our country well. Yet we have gained much too: a new champion, an invigorated campaign, and a renewed sense of purpose." 

Clinton said in an August interview that Harris was the "underdog" in her election fight against former President Trump because of the Electoral College. Clinton won the popular vote in 2016 but lost the swing states she needed to get into the White House.

"We are the underdog, that just kind of goes with the territory when we have the Electoral College staring at you, and we all have to be willing to take whatever steps to support her," Clinton told The 19th News last month.

The Harris campaign did not immediately respond to a request for comment from Fox News Digital. 

Fox News' Hanna Panreck contributed to this report.