California Sen. Barbara Boxer to retire in 2016

Longtime Democratic Sen. Barbara Boxer of California announced Thursday that she will not seek a fifth term in office.

"I will never retire from fighting for the issues that matter, but I will not be running for the Senate in 2016," the 74-year-old liberal lawmaker wrote on Twitter.

Boxer was elected the House of Representatives in 1982 and was elected to the Senate in 1992. She joined the Senate just months after California's senior senator, Democrat Dianne Feinstein.

Boxer explained her decision in an interview with her grandson Zach Rodham (the senator's daughter, Nicole Boxer, was once married to Hillary Clinton's brother Tony Rodham).

"I want to come home to the state that I love so much, California," Boxer said in the interview, which was posted on the website for Boxer's political action committee.

Unlike some other lawmakers to retire in recent years, Boxer said she was not inclined to leave Washington because of political acrimony.

"You know, when you stand up there, when you fight to make sure there's a strong middle class, and you protect a woman's right to choose, and you fight for jobs and a clean environment, all those things -- human rights, civil rights -- that's a fight worth making, so that is not a factor in my decision," she told her grandson.

Furthermore, she added that age was not a factor. "I feel as young as I was when I got elected," she said.

House Minority Leader Nancy Pelosi, another California Democrat, learned about Boxer's decision from reporters Thursday morning and was clearly surprised and saddened by the news.

"Her leaving will be a great loss to the Congress of the United States, to the people of California and to our country," Pelosi said, calling Boxer "small in size but a giant in terms of her contribution to our country." She specifically commended the senator for her work promoting economic fairness, environmental protections and assisting veterans.