Incumbent U.S. Senator Barbara Boxer (D-Calif.) announced in January 2015 that she will not run for re-election in 2016, leaving her senate seat open for the first time in three decades.

California has a non-partisan “jungle” primary in which the top two vote-getters will compete in the general election regardless of party affiliations. Senate primaries are held the same day as U.S. presidential primaries June 7. The general election is also held the same day as the presidential election Nov. 8.

The five main contenders are Tom Del Beccaro (Rep.), Kamala Harris (Dem.), Loretta Sanchez (Dem.), Duf Sundheim (Rep.) and Ron Unz (Rep.). The polls currently show Kamala Harris in the lead.

Tom Del Beccaro

He is best known for serving as the chairman of the California Republican Party from 2011 to 2013, and is currently a Forbes columnist on tax policy and politics. His positions are in line with social conservatives and neoconservatives.

Del Beccaro supports California Proposition 8, which eliminates the rights for same-sex couples to get married, though he said he is open to debate about the topic.

He believes that American presence in the Middle East will provide regional stability, and opposes to President Obama’s Iran nuclear deal.

Del Beccaro currently is tied with Sundheim in the most recent poll, sitting at nine points.

Kamala Harris

Harris is currently the Attorney-General of California, seen as a rising-star in her party.  She has also received a massive number of endorsements including Governor Jerry Brown, Senator Elizabeth Warren (D-Mass.), a speculated VP pick for the Democratic nominee in the Presidential race.

She has a commendable lead of 9 points to her closest contender, a fellow Democrat, in the most recent poll, which guarantees her place in the general election.

Her policy positions are best described in-line with the Democrat party establishment with emphasis on social issues like LGBT rights and abortion rights. She is against mass incarceration for nonviolent drug offenders, but has been cautious about her position on marijuana legalization.

Loretta Sanchez

Sanchez have been serving as a representative in the House of Representatives for the past 19 years for Orange County. She had served in various House committees related to military and security issues like House Armed Service Committee and House Homeland Security Committee.

She is currently placed second in the polls, with an insurmountable 13-point lead over the next closest contender, thus locking out the Senate bid for the Republicans.

Her issues revolve around the military: keeping America safe and defending the rights of women in uniform. It is also notable that “human rights” is one of the main issues in her campaign website. Otherwise, her policy positions are also in-line with the Democrat party establishment. She has endorsements from a number of fellow representatives in the House.

Duf Sundheim

Sundheim known best as the chairman of California Republican Party from 2003-2007, bringing in various reforms to the organization. He is endorsed by Kevin McCarthy, the current House majority leader.

His campaign message revolves around revitalizing local economies by making it easier for small businesses to take out loans and loosening regulations. He is a ferocious critic of the proposed high-speed rail project, arguing that there are better places to use the funds. One of his other main issues is ending common core.

Sundheim is also a ferocious critic of Kamala Harris, arguing that she serves the interest of her donors and that she is inefficient. In fact, there is a whole tab in his campaign website dedicated to her called “Kamala Facts.”

Ron Unz

Unz is the odd one out. He is the only non-establishment candidate (though currently running as a Republican) to appear on the Senate primary debate in April. His main issue is to bring attention to the efforts to repeal California Proposition 227, a bill Unz sponsored, which requires “Limited English Proficient” classes to be taught in English.

He had raised the issue of a livable minimum wage in an article published in 2011, and has been picked up by the Democrat Party. Minimum wage is now one of the main issues the Democrats advocate.

He currently sits at the polls at seven percent, bottom of the top five contenders.

by JUSTIN KWOK