A major second wave of cuts to the New York City library system has been averted in an 11th-hour deal announced on Thursday by the City Council and Mayor Eric Adams.

The restoration of $58 million in proposed cuts to the city’s three major library systems, part of a broader city budget agreement expected to be announced on Friday, has been one of the main focal points of the City Council speaker, Adrienne Adams. It is expected to allow libraries to reopen on Sundays and remain open on Saturdays.

The budget, which is due on Sunday, will also restore $53 million in funding for arts institutions, according to the announcement.

The mayor’s office and the City Council are in the final stages of negotiations, and deliberations have been contentious, with the two sides unable to agree on basic revenue estimates.

Mr. Adams, a Democrat who is running for re-election next year, had initially proposed major cuts to schools, police and sanitation services, citing pessimistic revenue projections and the continued financial burden associated with an influx of migrants into the city.

But the mayor’s revenue projections were widely criticized as being overly pessimistic. The City Council, the Independent Budget Office and various watchdog groups cited economic indicators that suggested that the mayor’s revenue projections were inaccurate. Even the fiscally conservative Citizens Budget Commission in April called the administration’s revenue projections “unreasonably conservative.”