WASHINGTON (AP) — Vice President Joe Biden says he won't run for president in 2016.

His decision finalizes the Democratic Party's field of White House candidates and sets Biden on a glide path toward the end of his decades-long political career.

Biden spent months deliberating with his family and political advisers about a potential late entry to the Democratic primary.

But he also said he might not be emotionally ready to run after his 46-year-old son Beau died of brain cancer in May.

Biden's decision bolsters Hillary Rodham Clinton's standing in the Democratic primary by sparing her a challenge from the popular vice president.

Democratic presidential candidate Bernie Sanders says Vice President Joe Biden has made a decision "that he feels is best for himself, his family and the country."

The Vermont senator is calling Biden his "good friend" and is thanking the vice president for "a lifetime of public service."

Sanders says Biden understands the need to rebuild the middle class and address income and wealth inequality.

Biden's decision not to seek the presidency leaves Sanders and Hillary Rodham Clinton as the leading Democratic candidates to succeed President Barack Obama.