Here's a look at Joe Biden's 50-plus year political career

President Joe Biden said Sunday he would not seek a second term as president, amid intense pressure from within the Democratic Party to step aside amid signs of cognitive decline. 

Biden began his elected political career in 1970 when he won an open seat on the New Castle County Council in Delaware.

Two years later, he defeated Republican incumbent J. Caleb Boggs, in a bare-boned campaign to become the junior U.S. senator from Delaware.

The 81-year-old Biden was born in Scranton, Pennsylvania, on Nov. 20, 1942. His family moved to Delaware when he was 7 years old. He attended the University of Delaware, then Syracuse University law school, from which he graduated in 1968.

He served in the Senate for 36 years, during which he was chairman of the powerful Senate Foreign Relations committee. 

In addition, he oversaw in 1991, the confirmation hearing for Clarence Thomas. The Judiciary Committee referred Thomas's nomination to the full Senate before allegations of sexual harassment against Thomas surfaced.

Biden reopened the committee's confirmation hearing to investigate the allegations against Thomas.

The Senate ultimately confirmed Thomas after acrimonious proceedings that Thomas referred to as a "high tech lynching."

Biden left the upper chamber in 2009 to serve as vice president under former President Barack Obama. Biden served two terms, until 2016.

Obama successfully dissuaded him from running for president in 2016, favoring Hillary Clinton, who was Obama's secretary of state. 

Key moments of Biden's presidency included rejoining the Paris Climate Agreement, revoking Keystone XL pipeline permits, and signing a nearly $2 trillion stimulus package to promote economic recovery post-COVID.

However, his presidency also was mired in controversy, including allegations that he profited from son Hunter Biden and brother James Biden's overseas business deals. The family used the Biden name to help them close deals, including Hunter Biden making millions as a board member of the Ukraine energy exploration and production holding company known as Burisma Holdings Limited.

House Republicans opened an inquiry into the matter, but were unsuccessful in their efforts to impeach Joe Biden.

He also was the subject of a Justice Department special counsel probe into his handling of classified documents after he left the Obama administration.

Special counsel Robert Hur found evidence that Biden willfully retained and shared highly classified information when he was a private citizen but then concluded that criminal charges were not warranted.

Other areas of controversy involved the Biden administration's open border policy, the high rate of inflation and the alleged weaponization of the Department of Justice.