“Unfortunately, I believe we’re out of time, the time necessary to mount a winning campaign for the nomination,” Biden said.
The announcement came as a surprise to many, including presidential hopefuls and other major political players.
In a statement released from the Vermont senator's office, Sanders wrote, “Joe Biden, a good friend, has made the decision that he feels is best for himself, his family and the country."
GOP presidential hopeful Donald Trump also weighed in on Biden’s announcement, tweeting he “would rather run against Hillary because her record is so bad.”
Republican hopeful Ben Carson also reacted to Biden's decision not to run, telling ABC News the vice president has to do what feels right:
“Well you know [Biden] has to do what he feels is right in his heart. It pretty much guarantees that Hillary will be the person that we're running against."
Sen. Rand Paul, R-Ky., tweeted:
Former Arkansas Gov. Mike Huckabee joined his fellow candidates on Twitter.
Democratic candidate Martin O'Malley issued a statement commending the vice president for his years in public service:
"Vice President Joe Biden is a very good and decent man who has served our country nobly, and his experience would have been a welcome addition to the Democratic race. I will always admire his strength in the face of adversity and his passion for bettering our country. I respect Vice President Biden's decision today and wish the Vice President and his family well."
The former Maryland Gov. also shared his thoughts on Twitter:
Rep. Brendan Boyle, D-Pa., expressed surprise at Biden’s decision. Boyle had tweeted earlier this week that a source close to Biden told him the vice president was sure to run.
“Clearly something changed,” Rep. Boyle tweeted.
“While Vice President Biden will not be a candidate next year, his unwavering commitment to America’s working families is a legacy each of our candidates will proudly carry forward.”
Wasserman Schultz, who worked on Biden’s campaign for president in 1988, tweeted:
So what's next for Biden after he leaves office?
One Massachusetts congressman raised the question on Twitter:
Executive Director of Draft Biden 2016 Will Pierce issued a statement expressing gratitude for the “outpouring of support” as the vice president weighed a White House bid:
"We are so grateful for the gigantic outpouring of support from hundreds of thousands of Americans around the country in our effort to encourage the Vice President to run. While the Vice President has decided not to run, we know that over the next year he will stand up for all Americans and articulate a vision for America's future that will leave no one behind."