* Union leader declines to predict outcome of vote
* Contract sets 17.6 percent pay rise over four years (Updates with Fitch downgrade, reaction; quotes from Duncan)
By James B. Kelleher
CHICAGO, Oct 2 (Reuters) - Chicago public school teachers began voting on Tuesday on whether to ratify an agreement with Mayor Rahm Emanuel that suspended a strike in the third-largest U.S. school district.
The Chicago Teachers Union has urged its 29,000 members to ratify the proposed contract, which calls for an average 17.6 percent pay raise for teachers over four years and some improvements in benefits.
Union President Karen Lewis declined to say whether members would ratify the deal. "I don't have a crystal ball," she said.
Approval of the deal, by a simple majority vote, would officially end the teachers' strike, which was suspended on Sept. 18 after seven school days.
However, the deal could be costly to the school district and the financial consequences already are being felt.
Fitch Ratings downgraded the Chicago Board of Education's debt rating, citing the school system's increased budget pressures in the wake of a tentative agreement. This followed a downgrade by Moody's Investors Services last week and could mean the district pays higher interest rates on any debt issues.
In a statement responding to Fitch, the school district said it sees a $3 billion deficit over the next three fiscal years.
"Chicago Public Schools is facing both an educational and financial crisis after years of revenue losses and misplaced priorities," it said.
The pay increases would cost an extra $74 million a year, it said. Chicago teachers make an average of about $76,000 annually, according to the school district.
Kristine Mayle, the union's financial secretary, said voting would take place before and after classes on Tuesday at more than 600 schools and other facilities across the city. Results are expected late Wednesday night or Thursday morning, she said.
"We have couriers going out to pick up the materials and we'll be counting as fast as they bring them (votes) back to us," Mayle said.
Teachers are expected to ratify the deal, Mayle said. Last month, about 800 union delegates overwhelmingly decided to suspend the strike after reviewing the contract.
U.S. Education Secretary Arne Duncan, a former chief executive of Chicago Public Schools, said both sides won in the agreement. "Despite the tough acrimony, at the end of the day they got to a contract that I think was very fair," he told reporters in Washington.
The strike placed Duncan and President Barack Obama in a tough spot because it pitted Emanuel, Obama's former White House chief of staff, against a major labor union that supports Obama.
CULMINATION OF LONG SHOWDOWN
The teachers' walkout on Sept. 10, which canceled classes for 350,000 students, was the culmination of a long showdown with Emanuel, who had pushed for sweeping education reforms.
The strike was the first by Chicago teachers in 25 years and focused attention on a national debate over how to improve failing schools.
Emanuel, backed by a powerful reform movement, believes poorly performing schools should be closed and that parents should have more choices among public schools, including "charter" schools that often are non-union and run by private groups.
Union leader Lewis spoke in front of Dyett High School, on the city's south side, which was slated for closure and criticized the district for not listening to the community.
"It was clear that when this school was put on the hit list that the voices of the community and the parents and the children were not heard - or were heard and ignored - which is, I think, even worse," Lewis said.
Dyett, which has fewer than 200 students, has been on probation for seven years, according to the district, and fewer than 10 percent of its juniors met state standards in a two-day standardized test taken by all high school juniors in Illinois.
Teachers want more resources put into neighborhood public schools to help them succeed. They say many of their students live in poor and crime-ridden areas and this affects their learning. More than 80 percent of public school students qualify for free meals based on low family incomes.
Emanuel secured a new teacher evaluation system based in part on student standardized test scores, but he compromised on the weight given to the test scores. He also got new flexibility for principals to hire teachers.
Teachers won some job security for colleagues laid off when schools are closed. Union teachers will be the first hired when the district adds teachers.
In downgrading the Chicago Board of Education's debt last week, Moody's said other contributing factors included district plans to spend its reserves to fund operations in fiscal 2013, an "impending spike" in pension payments for retired teachers and continued delays in securing state aid. (Additional reporting by Susan Heavey and Karen Pierog; Writing by Mary Wisniewski; Editing by Greg McCune and Christopher Wilson)