Two sisters greet each others after taking part in a special morning prayer to start their Eid al-Fitr festival, which marks the end of Muslim's holy fasting month of Ramadan, outside the Baitul Ma'Mur Mosque in Brooklyn, New York, on Sept. 20, 2009. Jewel Samad/AFP/Getty

After a new mayor takes office in New York City next year, schoolchildren could very well have an additional two days off in observance of Muslim holidays. Both mayoral candidates, Democrat Bill de Blasio and Republican Joe Lhota, say they support the idea. If such a measure were to come to pass, the New York City school district would be the largest in the United States to grant the days off.

De Blasio said during a campaign rally with local Muslims on Wednesday that observing Eid al-Fitr, which marks the end of Ramadan, and Eid al-Adha, a celebration during hajj, would help to recognize the city's large Muslim population and wouldn't take away from the education kids get.

"A child who has an exam on a day that right now is one of the Eid holidays, they're either respecting their religious obligation or they're doing what their education requires of them," de Blasio said, according to the New York Daily News. "They can't do both under our current system."

About 13 percent of the city's schoolchildren are Muslims, de Blasio added.

His Republican rival, former city transit chief Joe Lhota, also said that adding the holidays would be a good idea. Students would come to school on two other days to make up for the holidays, he said.

"We have a growing Muslim community in the city of New York and their religion needs to be respected as all other religions are respected," Lhota said Wednesday, according to the Daily News.

Outgoing mayor Michael Bloomberg opposes the idea. He has said that observing the holidays would take away from students' education and open the door to similar requests from other religious and ethnic groups.

In 2009, the city council approved a measure that would have added the two holidays to the school calendar, but Bloomberg opposed it. A 2010 New York state measure, which could have forced the city to add the holidays, stalled in the legislature.

The city's school district already observes Christian holidays like Good Friday and Christmas, as well as Rosh Hashana, the Jewish new year, and Yom Kippur, the holiest day of the year for Jewish people.

Other school districts across the U.S. already observe Muslim holidays.

Dearborn and Dearborn Heights, both in Michigan, allow three days off in observance of the holidays because of the towns' large Muslim populations. Like Rosh Hashana, the holidays happen according to a lunar calendar, so their dates change year to year.

School districts in Massachusetts and Vermont also close for at least one Muslim holiday each year.

Abed Ayoub, the legal and policy director of the American-Arab Anti-Discrimination Committee told Al Jazeera that not adding the two Muslim holidays to school calendars means kids often end up skipping school to observe.

"When you have so many students absent it causes a problem," Ayoub said.

School attendance was noticeably down in New York City on Eid Al-Adha on Tuesday, the Daily News reported.

The Council on American-Islamic Relations (CAIR) has also pushed the school district in Montgomery County, Md., a suburb of Washington, to add days for Muslim holidays to its calendar.

"Parents should not be forced to choose between religious observance or the education of their children simply because they're of a different faith," CAIR-MD Vice President Zainab Chaudry said, according to a statement provided to Al Jazeera by the organization.

"We want to emphasize that Montgomery County American Muslims don't seek special treatment, but rather equal treatment. This is a civil rights issue."