Mendoza said expanding those county boards of supervisors from five to seven members would improve how county boards represent citizens in California's largest counties and allow more diversity on the panels.
"California's population and demographics have changed significantly since the formation more than one-hundred and sixty-five years ago of representative governmental entities known as counties," Mendoza said in a statement. "Residents of California's largest counties deserve a more representative and responsive government at the county level."
State Constitutional Amendment 8, introduced Monday, would have to win the vote of a two-thirds majority of the California Legislature to make it to the ballot. That will require some Republican support.
Mendoza said county supervisors in the largest counties each represent 400,000 to more than 2 million residents.
The small size of the boards of supervisors hinders opportunities to increase ethnic diversity on the panels so they better reflect the demographics of the counties, Mendoza said.
He noted that in the five largest counties, only two of the 25 board members are Latino, even though in three of those counties, Latinos make up nearly half the population.