According to a statement from her family, Tauscher died Monday at Stanford University Medical Center from complications from pneumonia.
Tauscher represented the East Bay in Congress from 1997 until 2009, when she resigned to serve in the State Department under President Obama.
At that time, she announced she was battling esophageal cancer, which she eventually beat.
Senator Dianne Feinstein issued a statement Tuesday morning saying, "Ellen was brilliant, gracious and generous and always did her level best to lift up those around her."
Former Governor Jerry Brown issued a statement to Politico: "Ellen was a friend, a great personality and a real force on critical issues that affect California and the world. She'll be greatly missed."
Tauscher most recently served on the board of the University of California Regents.
Funeral plans have not been revealed.
Bill and I are deeply saddened by the passing of our dear friend Ellen Tauscher. Ellen woke up every day determined to make a difference, and make a difference she did. pic.twitter.com/86BRmtB4Qt— Hillary Clinton (@HillaryClinton) April 30, 2019
Read the statement from Tauscher's family below:
"It is with the greatest sadness in our hearts that we announce the passing of our beloved mother, sister, aunt, and friend, Ellen O'Kane Tauscher. Ellen died peacefully surrounded by her loving daughter, Katherine, and the rest of her family.
"Ellen was a force to be reckoned with from the time she was a young girl growing up in Harrison, New Jersey. She succeeded at everything she did and made her mark wherever she went. She was the strongest, bravest person we have ever known, and while she beat a cancer in 2010 that most people don't survive; she lost the battle against pneumonia that she had been waging since January.
"While we knew her as the defining force in our family - either as the mother who fought to make sure Katherine would be able to live a full life after being born premature or as the oldest sister who broke barriers and forged new paths that all of us would later follow - the public knew her for the history she made throughout her life.
"As the youngest and one of the first women to hold a seat on the New York Stock Exchange, Ellen broke barriers for generations of women that followed her into the male-dominated world of finance. She was the author of the Childcare Sourcebook in the 1990's and founded the first national research service to help parents verify the background of childcare workers.
"In 1996, Ellen ran and won an historic election for Congress, winning a Republican seat that no one thought a Democrat would win that year. In the House, she chaired the Strategic Forces subcommittee of the Armed Services Committee, among other leadership positions. Public service was her calling, and there was no job she loved more than representing the people of Contra Costa, Alameda, and Solano counties for seven terms in Congress.
"Ellen completed her career in public service when President Obama appointed her and the U.S. Senate confirmed her as Undersecretary of State for Arms Control and International Security Affairs in 2009. As we came to expect from Ellen, she tackled the job with her trademark gusto by completing negotiations of the New START treaty with the Russians and working for non-proliferation around the world.
"After three years at the State Department, working under Secretary Hillary Clinton, Ellen retired from public service in an official capacity; but continued to serve the country and the State of California as Chair of Governor Jerry Brown's Military Advisory Council, chairman of the Board of Governors for Livermore and Los Alamos labs, and as a UC Regent.
"While she accomplished so much professionally, Ellen always said that her proudest accomplishment was her daughter Katherine. And it is that grounding in love for family and friends for which we will always cherish her memory.
"It's been said that God created humans because he loves the stories. And Lord knows, Ellen's were among some of the most remarkable stories of survival and strength, of living to the fullest and giving to others with every ounce of her strength. Those stories will live on inside the broken hearts of her friends and family on whom she has left on an indelible mark. Ellen came and made a difference in the lives of her neighbors and perfect strangers who trusted Ellen with their votes and their futures. And she never let them down. You can see Ellen's legacy in the lives made just that much better, that much safer, that much more secure in the East Bay, in California, in America, and across the world.""