After serving over two decades in office, Democrat Sen. Barbara Boxer, who solidified her name as the liberal firebrand of California politics, had said she will step down in 2016. All eyes will now be focused on Boxer’s California seat following her early retirement announcement, which will leave plenty of time for candidates to strategize.

Boxer’s likely successor will be a Democrat, with members of that party who could be vying for that slot in no short supply. Yet while it will likely prove to be an uphill battle for Republican candidates, there are a few who might consider taking a stab at the seat. Here is a list of the top contenders.

Democrats:

Tom Steyer: Billionaire hedge fund manager and environmentalist with a specific emphasis on global warming. In 2014, Steyer and his wife were the top individual political donors in the nation, giving $75 million to help Democratic candidates who shared the Steyers’ views that global warming is the eminent threat facing America.

Kamala Harris: California’s first African-American attorney general. She is commencing her second and final term as the Golden State’s top law enforcement official.

Gavin Newsom: Lieutenant Governor of California, who is serving his second term in that office. Newsom became the youngest mayor of San Francisco in 100 years when he won election at the age of 42 in 2003. He was sworn in to his second term as Kamala Harris on January 5.

Jerry Brown: Governor of California who was just sworn in for an historic, unprecedented fourth term. He is California’s longest-serving governor. However, whether he would be willing to take the position of Senator after having such power at governor is up for debate. Brown’s political aspirations would likely involve a potential Presidential bid.

Angelina Jolie: Hollywood A-list actress and humanitarian who has expressed her interested in running for political office. Most recently, she hinted at it in a December of 2014 interview with NBC News’ Tom Brokaw.

Antonio Villaraigosa: Served as the 41st Mayor of Los Angeles for eight years. He is currently a  professor of public policy at the USC Price School of Public Policy. He has stated his interest in running for governor or president in the past. Perhaps a Senatorial run is also in his sights.

George Clooney: Actor and activist who has explicitly stated his intent to become more involved in politics.

Republicans:

Darrell Issa: Congressman for California’s 49th Congressional District since 2001 and the wealthiest member of Congress currently serving. Issa reportedly owns the domain name IssaForSenate.org. However, advisors close to him revealed today that the domain registration should not be read into much. Issa has stated openly that California has become deeply Democratic over the course of the last 10 years, which would make it unlikely a Republican could win blue seats anytime soon.

Charles Munger: Billionaire Stanford physician who is staunchly against raising taxes on the wealthy and who has personally funded an array of Republican candidates to help broaden the GOP’s representation in California’s political demographic.

Kevin Faulconer: Mayor of San Diego who defeated Democratic opponent David Alvarez to replace disgraced Mayor Bob Filner this past November. It is unlikely, however, that Faulconer will give up his mayoral status to run.

Ashley Swearengin: Mayor of Fresno, California. Swearengin ran an unsuccessful campaign for State Controller against Democratic incumbent Betty Yee, who won reelection in the primaries in November. She is Fresno’s second female mayor.

Neel Kashkari: Former gubernatorial candidate who lost by a substantial amount of votes to incumbent Governor Jerry Brown. Kashkari served as assistant secretary under the government’s Troubled Asset Relief Program (TARP). He had spent millions of his own funds trying to defeat Gov. Brown with a series of television ads. It is believed he had placed such great emphasis on publicizing his campaign despite Brown’s projected victory, as a way to set the stage for a potential future political run.

Adelle Nazarian is on Twitter @AdelleNaz