Transit and low income advocates joined elected officials outside City Hall Sunday to call for a reduced fare MetroCard for the poorest New Yorkers.

A study released by the nonprofit Community Service Society found that one in four low income New Yorkers can’t afford MetroCards. For 300,000 straphangers, the cost of taking a subway exceeds 10 percent of their income.

The Riders Alliance said the MTA should offer a low-income discount in the same fashion that it provides relief to disabled riders, senior citizens and younger students.

“Public transportation should mean access to jobs and economic opportunity, but that can’t be true if you can’t afford it,” Riders Alliance president John Raskin.

Under one proposal, any adult between 18 and 64 who is under the federal poverty level would be eligible for a MetroCard charging $1.35 per ride. Harold Stopler, an economist for Community Service Society, who cowrote the report, said there could be several ways that the city and state could pay for those cards, including funding from the city budget and an increase from the gas tax.

Public Advocate Letitia James and City Comptroller Scott Stringer back the low-income reduced fare MetroCard proposal, which is similar to ones enacted in Seattle, San Francisco and other smaller cities.

The MTA had no comment on the proposal.

Representatives from the governor’s office didn’t respond for comment, but a spokeswoman for the mayor’s office called the proposal interesting.

“We look forward to reviewing the report in greater detail,” she said in a statement.