The backlash to Trump, combined with the enthusiasm for Bernie Sanders, has contributed to a bonanza of new Democratic voters in San Diego County. This presents both an opportunity and a challenge. Since January, we've seen an increase in the Democratic voter registration advantage over Republicans grow 153%. That is increasing at a record pace. We're ready to engage, inform, and turn them out to vote in November for all our endorsed candidates, from the President to local city councils and school boards.
Over the past ten years the San Diego County Democratic Party has steadily increased our capacity for turning out voters and winning elections. With over 70,000 newly registered Democrats in the county this year alone, we will be putting all our energy into empowering our volunteers and candidates to engage with voters for a record-setting election turnout in November.
The primary election was a bellwether of what we can expect in November. Countywide we saw a surge in turnout for Democratic candidates. A whopping 61% of voters in the county cast their votes for Democratic presidential candidates, versus 38% who voted for Republican candidates. In the race for U.S. Senate, Democratic candidates earned 58% of the votes, versus 35% for Republicans. Fully 75% of candidates endorsed by the San Diego County Democratic Party won outright or qualified for runoff election in November.
Our GO Team, the Grassroots Organizing precinct program, deployed 463 members who walked door-to-door or made calls to 40,872 voters in support of our endorsed candidates under the supervision of 29 community coordinators. That was a record number of GO Team members in a primary election. With that kind of participation in the primary, we anticipate an army of GO Team volunteers engaging with voters leading up to the general election.
One of the most effective resources that we provide as a political party organization is our ability to coordinate with the campaigns of our endorsed candidates. During the primary election, we raised and spent $542,300 in support of our candidates. We opened campaign offices in Chula Vista and Escondido as well as making our headquarters available for phonebanking and other campaign activities. We mailed 33 informative campaign pieces to hundreds of thousands of voters in coordination with the campaigns. Just a few years ago, we would never have dreamed that this would be possible.
Since last year, we have been recruiting, training, and mentoring candidates throughout the county to run this November. More candidates are continuing to emerge as the date for candidate filing opens next week. This is the earliest head-start that we've had in positioning our candidates for our endorsements and preparing them to run for office. We will offer our endorsed candidate training in Campaign Organization, Messaging and Communications, Finance and Fundraising, and Field Operations on August 27. I have made campaign training and support a priority during my term as Chair to ensure that candidates have the confidence and knowledge needed to run strong as part of a countywide coordiated team effort.
Finally, we are reaching out to Democrats for financial support. The generous support of our DEM (Donate Every Month) donors, other major supporters, and all those who contribute to the San Diego County Democratic Party at any level make it possible for us to maintain our office, staff, technology, communications and financial systems, voter registration, and candidate support programs. I hope that you will become a DEM donor or make a contribution today and join our GO Team. With your support, we'll be celebrating successes from the White House to every corner of our county on November 8.