As voters across California head to the polls this Tuesday, San Diegans will cast their ballot for one of the four candidates running in the city's heated mayoral race: City Council Member Carl DeMaio (R), Congressman Bob Filner (D), State Assemblyman Nathan Fletcher (I), and District Attorney Bonnie Dumanis (R).

The competitive nature of this race has led to a reported $6.5 million spent as of Friday, with over $4.4 million spent by the candidates themselves. In addition to campaign fundraising, political-action committees have spent a reported $2 million on this race.

San Diego Voter Demographics 

With 1.4 million registered voters, San Diego County boasts a unique voter demographic. What used to be a strongly Republican city has become increasingly Democratic in the last decade, with the majority of voters now identifying with the Democratic Party.

As reported by the Associated Press,

"Democrats overtook Republicans in voter registration in 1994 and now hold a 12-point edge in voter registration… San Diego, like the state, has favored the Democratic nominee for U.S. president since Bill Clinton won in 1992."

Despite the city's growing number of registered Democrats, however, Republicans have held onto the seat of Mayor since 1992 due to their success at recruiting candidates, campaigning, and a well-organized Republican base.

This election, however, departs from the traditional partisan battle, with 35-year-old veteran and former State Assembly Member Nathan Fletcher challenging his opponents as an Independent. After leaving the Republican party in March, Fletcher's popularity increased dramatically as he spread his nonpartisan message.

Recent Polling Reveals a Race for Second Place 

If no candidate receives the majority of votes, then the top two candidates with the most number of votes will face off in November's election.

The most recent poll from 10news/SurveyUSA shows that as of May 31st, just five days before the primary, Carl DeMaio leads with 31% of the likely vote, closely followed by Bob Filner. The full results are as follow:

31% Carl DeMaio, 11% Bonnie Dumanis, 28% Bob Filner, 23% Nathan Fletcher, 3% Other, 4% Undecided. Margin of Sampling Error for this question = ± 4.3%

While these numbers show a slight lead for DeMaio, KPBS reports "compared to an identical poll that was released 17 days ago, DeMaio is flat, Filner is up 7 percentage points and Fletcher is up 2."

As noted in a May 31st Press Release from Independent Super PAC icPurple, when No Party Preference voters learn that Nathan Fletcher is an independent, he becomes their likely candidate, speaking to the importance of independents in the San Diego race.

Last Minute Campaigning

So how are the candidates spending the last hours before the election? Carl DeMaio is holding his final community coffee night, inviting San Diego voters to meet with him over coffee and discuss the issues. Democratic challenger Bob Filner is traveling all across the city, making some last minute appearances at San Diego retirement communities and Veterans Village locations.

Republican turned Independent Nathan Fletcher relies heavily on social media in an effort to get out the vote. Encouraging his followers to change their profile pictures and wave Fletcher signs outside polling locations, Fletcher has been very active on both Facebook and Twitter. After participating in yesterday's San Diego Rock 'N' Roll Half Marathon to benefit The Leukemia & Lymphoma Society, he hit the streets, walking door-to-door and calling San Diego residents.

Meanwhile, Republican Bonnie Dumanis spoke on the local radio show "Dave, Shelly and Chainsaw" this morning, discussing her experience as District Attorney.

San Diego Key Issues

This year, San Diegans are presented with a pressing set of issues, ranging from pension reform to keeping the San Diego Chargers stadium in the city. At a recent debate, DeMaio highlighted the importance of the race:

"This is such an important election for San Diego…It will determine whether we move forward and finish the job of fiscal reform, to fix our streets and restore our services -- to help create jobs in San Diego." 

Among the key issues facing San Diego is the condition of the local streets. Plagued with potholes, the streets of San Diego have suffered immensely from the cutbacks in state funding and resurfacing has been put on hold.

Proposition A and B will also come into play, as residents will be voting on the two measures in tomorrow's primary.

Want to learn more about the candidates? The Voice of San Diego created this mayoral "scorecard" to compare where the candidates stand on issues: