Oct 28 (Reuters) - About 300,000 students in Chicago will miss classes for an eighth day on Monday, as the teachers' union and public school district failed over the weekend to resolve a deadlock in contract talks over class sizes, support staff levels and pay.
Each side blamed the other for the impasse in the United States' third-largest school district, where the strike began on Oct. 17, and the union, which represents the city's 25,000 teachers, has been without a contract since July 1.
Mayor Lori Lightfoot and the Chicago Public Schools' chief executive, Janice Jackson, blasted the Chicago Teachers Union in a joint news conference on Sunday for not accepting the school system's offer.
"We are enormously disappointed that CTU cannot simply take yes for an answer," Lightfoot said before listing the specifics on offer, including "a big, 16 percent raise for teachers."
She added, "At every turn we've met CTU's demands."
But the union blasted the mayor's assertions that the schools had met much of its demands, declaring that Lightfoot used "bad mayoral math" to describe the schools' offer.
"Sticking points at the table remain," including "contract language designed to rein in classroom overcrowding," union officials said in a late night statement.
"Put bluntly, the deal that CPS is touting will not set an enforceable class size standard for all schools."
The union also wants more support staff, a contract that runs three years instead of five, and more paid prep-time for elementary school teachers.
The weekend saw some progress however, as the union representing some school support staff made a tentative deal to end the strike, Lightfoot announced, covering custodians, security officers and bus aides.
But media, including the Chicago Times, said late on Sunday that 7,500 members of the Service Employees International Union (SEIU) would not cross the CTU picket lines. The terms of the SEIU agreement were not immediately available.
On Friday, officials had been more optimistic for children to be back in school after the weekend, with the leader of the Chicago Teachers Union saying he was hopeful the previous day's talks had given the path towards a settlement.
"Right now I’m guardedly optimistic," President Jesse Sharkey told a news conference.
Related: Chicago, Illinois
Striking teachers rallied again later on Friday at Chicago's Buckingham Fountain, however.
The strike is the latest in a wave of teacher work stoppages across the United States, some of which, such as a six-day work stoppage last winter in Los Angeles, have involved similar demands for more school resources.
It has lasted longer than walkouts elsewhere, except for a three-week strike by teachers in Union City, California in June.
President Donald Trump plans to be in Chicago on Monday for a speech and fundraiser for a grouping of international police chiefs that is expected to draw thousands of protesters as well as supporters, Politico and other media said.
But it was unclear how the planned protests and picket lines of the striking teachers would affect traffic and police resources.
Lightfoot, a political newcomer elected in April, faced her first major test after Chicago teachers voted to strike following the failure of contract talks to strike a deal on pay, class overcrowding and a lack of support staff.
She has said the district could not afford the union's full demands, estimating they would cost an extra $2.4 billion each year for an increase of more than 30% in the current $7.7-billion school budget. (Reporting by Rich McKay in Atlanta; Additional reporting by Brendan O'Brien in Chicago; Editing by Clarence Fernandez)