During the 1859 general elections, Lecompton Democrats voted for Milton Latham, who had briefly lived in the American South, as their nominee for governor.

The infant Republican Party, running in its first gubernatorial election, selected businessman Leland Stanford as its nominee.

The main effort focused on making railroads public avenues of transportation similar to streets and roads.

The struggle between the anti-monopolists and the railroad companies was, however, a key and defining issue for the Democratic Party for some time.

While the Progressives were successful in creating positive reform and chasing out corruption, the movement drained away many of the Democratic Party's members.

As their movement ended, the Republicans won the governorship, but the Democratic Party had a distinct voter advantage.

In 1932, Franklin D. Roosevelt was elected president, and the Power balance between the Republicans and the Democrats in California equalized.

However, as Roosevelt's New Deal policies began to raise the nation out of the depression, Democratic strength mounted.

A strategy of re-organization and popular mobilization emerged and resulted in the creation of the California Democratic Council.

Starting with the double digit victory of Bill Clinton, this became the first time a Democrat had carried the state of California since 1964.

Afterwards, a consolidation of the Latino and Asian vote would strengthen the Democratic party's hold in California, when these groups had previously been considered core Republican supporters within the state.

President Clinton won California's 54 electoral votes, and two women, Dianne Feinstein and Barbara Boxer, were elected as U.S. senators.

The 1996 elections proved to be a dramatic turnaround from the results of 1994, as President Bill Clinton won California's 54 electoral votes for a second consecutive time.

Six of eight candidates for statewide constitutional offices won, including Lieutenant Governor Cruz Bustamante, Attorney General Bill Lockyer, Treasurer Phil Angelides, Controller Kathleen Connell, and State Superintendent of Public Instruction Delaine Eastin.

This feat (winning all statewide offices) was repeated in 2010, when, despite massive Republican gains nationwide, the California Democratic Party swept all the statewide offices being contested, maintained its 34–19 edge in the 53-member U.S. House delegation, and won one additional seat (thus increasing their majority) in the State Assembly, while maintaining their current majority in the state senate.

In the 2012 election, California Democrats experienced tremendous success once again: Not only did President Barack Obama win California's 55 electoral votes again, with over 60% of the vote, and Senator Dianne Feinstein was re-elected with over 62% of the vote, but California Democrats – despite running in federal and legislative districts that were redrawn by an independent redistricting commission for the first time, per the passage of Propositions 11 and 20, and the implementation of a new blanket primary – also won a net gain of four House seats by defeating three GOP incumbents and winning an open GOP seat, and won a supermajority in both houses of the state legislature, a feat which the party last accomplished in 1882.

[19][20] The Democratic State Central Committee (DSCC) is composed of approximately 2,900 delegates that are selected through a wide variety of manners.

[21] The executive board is composed of approximately 320 members and holds all powers and duties of the California Democratic Party while the DSCC or its conventions are not in session.

As of January 3, 2025, Democrats hold a 30–9 supermajority in the 40-member California State Senate following Marie Alvarado-Gil switching to Republican party.