Antonio Villaraigosa (AP Photo/Rich Pedroncelli, File)

Former Los Angeles mayor Antonio Villaraigosa has announced he will not run for the Senate in 2016, a decision that further bolsters state Attorney General Kamala Harris's frontrunner status.

"I am humbled by the encouragement I've received from so many to serve in the United States Senate," Villaraigosa said in a statement on Facebook. "But as I think about how best to serve the people of this great state, I know that my heart and my family are here in California, not Washington, D.C. I have decided not to run for the U.S. Senate and instead continue my efforts to make California a better place to live, work and raise a family."

Villaraigosa, a Democrat who in 2005 became the first Hispanic mayor of the Los Angeles since the 19th century, was seen as a top potential Harris foe. His decision comes after billionaire climate activist Tom Steyer, another top prospect, also declined to run.

Harris, also a Democrat, has attracted support from both California and national party leaders in her bid to succeed retiring Sen. Barbara Boxer (D). She is backed by Sens. Elizabeth Warren (D-Mass.) and Cory Booker (D-N.J.), who both have loyal followings.