Negotiations between the union representing teachers at 17 Philadelphia-area Catholic high schools and the archdiocese continued into a 14th hour late Monday night.

Talks, which began at 10 a.m., had been scheduled to end at 8 p.m., but the two sides were still meeting as of 11:30 p.m. in a down-to-the-wire race to resolve the contract dispute before the high schools' scheduled Wednesday opening. The marathon session followed six hours of bargaining Sunday and nine hours Friday. The contract expired at 12:01 a.m. Saturday.

"Sessions have started with both sides working hard at the table today," Jason Budd, the archdiocese's chief negotiator, said in a statement.

Union leaders had hoped to bring a deal to their 650 members at a meeting Tuesday morning at the Sheet Metal Works Local 19 facility on Columbus Boulevard. Classes are set to start Wednesday for the 11,600 students at the high schools. (Students enrolled at parish and regional Catholic elementary schools in the archdiocese are not affected, and their teachers are not unionized.)

The major points of contention were pay raises for teachers and protection against rising medical costs.

Last year's contract gave teachers a $1,200 raise across the board, with their 15 percent share of medical premiums remaining the same. Under the current contract, pay starts at $39,800. The highest-earning teachers, those with a doctorate and 40 years of experience, earn $80,505; top pay without a doctorate is about $79,000, with about 10 percent of teachers at that level.

In recent years, negotiations have gone up to the deadline, with one-year agreements being hammered out at the last minute. Last year, the two sides similarly bargained past the expiration and through the Labor Day weekend before agreeing to a deal the day before classes began.

The high school teachers last walked out in 2011. In May, the union members authorized a strike  — if leaders deem it necessary.

Spokespeople for the archdiocese have said that their proposals "ensure no teacher will experience a rise in cost for health benefits" and that salaries for the high school teachers are consistently ranked among the highest in the nation.

Rita Schwartz, the president of the Association of Catholic Teachers, has said that  "nobody wants a strike" but that both sides had remained far apart over the course of 16 negotiating sessions.