Harris, who has first elected to her post in 2010, has been widely expected to run for the seat currently occupied by Democratic Sen. Barbara Boxer. Boxer announced her intention to retire last week. It is the first time California has had an open Senate seat since 1992.
A Harris spokesperson did not immediately return The Huffington Post's request for comment.
Earlier Monday, California Lt. Gov. Gavin Newsom (D) said he would not seek the seat. Newsom hinted to the Los Angeles Times that he would support Harris if she chose to run, but denied that he and Harris had struck a deal in which he would back her Senate bid if she supported his gubernatorial aspirations.
“I’m a huge fan and supporter of hers, and so maybe you can read between the lines,” Newsom said. “But she has to process exactly what I went through: Is it really what you want, and is it the right time, and do you have something to offer, and is there a clarity to that contribution. If you can answer those questions, then go for it.”
Harris is on track to be the first candidate to officially jump in the race. Former Los Angeles Mayor Antonio Villaraigosa has said he is "seriously considering" running, while billionaire environmental activist Tom Steyer is also reportedly weighing a bid.
UPDATE -- 10:55 a.m.: Harris posted the following message to her website on Tuesday:
I’m excited to share with you that I’m launching my campaign to represent the people of California in the United States Senate.
Your support has been crucial to me every step of the way, and I’m asking you to help me build a grassroots campaign that reaches every community of California.
From my first days as a prosecutor in Alameda County, to my work as San Francisco District Attorney to my current service as California Attorney General, I have worked to bring smart, innovative and effective approaches to fighting crime, fighting for consumers and fighting for equal rights for all.
I want to be a voice for Californians on these issues and others that impact our state in the U.S. Senate. I will be a fighter for the next generation on the critical issues facing our country. I will be a fighter for middle class families who are feeling the pinch of stagnant wages and diminishing opportunity. I will be a fighter for our children who deserve a world-class education, and for students burdened by predatory lenders and skyrocketing tuition. And I will fight relentlessly to protect our coast, our immigrant communities and our seniors.
California has been incredibly well served by the transformational leadership of Senator Boxer and the continued service of Senator Feinstein. With your help, I hope to build on their legacies in the U.S. Senate.
I’m looking forward to seeing and talking with you in the coming days and months. In the meantime, I hope you will join me on this journey. We will do incredible things together.