Nonprofit workers who have been pushing for a raise above what was included in the mayor’s budget might end up receiving one, if a proposal by Supervisors David Campos and Eric Mar is adopted by the Board of Supervisors.

The two supervisors want the city to use any revenues above and beyond what’s expected for the fiscal year that ended June 30 for raises at nonprofits that contract with the city.

A resolution, introduced Tuesday, would put the board on record supporting using up to $3.4 million for raises at dozens of nonprofits. The money would amount to a 0.75 percent raise for hundreds of workers that serve San Francisco’s mentally ill residents, and people who have substance abuse problems and other challenges.

Those nonprofit workers are receiving a 1.5 percent pay increase under the budget approved by the supervisors Tuesday, but between 2008 and 2012 they didn’t see any increase in their city payments.

The resolution notes that nonprofit organizations in Northern California are seeing 13 percent turnover rates for full time employees, that for-profit city contractors have seen increases in their city payments every year and that elected city officials are receiving a 2.6 percent salary increase this fiscal year.

“We are dealing with an affordability crisis and if we really want workers who are doing the important work that they do, we have to make it so they can afford to stay in San Francisco,” Campos said. “This is a minor, modest adjustment consistent with what other folks have gotten.”

The resolution is purely advisory, Campos noted: To actually give the money to workers, the board would have to introduce and approve a supplemental appropriation.

Marisa Lagos is a San Francisco Chronicle staff writer. E-mail: mlagos@sfchronicle.com Twitter: @mlagos