LOS ANGELES » The nation’s most populous county could lift the minimum wage for some workers to $15 an hour by 2020, just weeks after the city of Los Angeles took a similar step.

The Los Angeles County Board of Supervisors is expected to take a preliminary step Tuesday that could lead to the higher wages.

A proposal would direct county lawyers to draft a proposed law gradually increasing the wage mark over several years, which the board would consider later this year.

If approved, the hourly wage would increase in steps until it hits $15 in 2020. Then, beginning in 2022, the wage would be increased annually based on inflation.

The vote is expected a day before Vice President Joe Biden travels to Los Angeles to promote a higher minimum wage.