ST. PAUL — Union officials who represent St. Paul public school teachers say they’ll decide Monday whether to put a strike to a membership vote after eight months of contentious contract talks.

The St. Paul Federation of Teachers and St. Paul Public Schools apparently made progress during about 12 hours of negotiation Thursday, but union President Mary Cathryn Ricker said the executive board will decide whether to call for a strike-authorization vote.

“It’s helpful to make incremental forward progress,” Ricker said. “But we’re serious about making progress on the issues that are most important to us.”

The two sides have struggled to agree on union proposals that include capping class sizes, reducing time spent on standardized tests and hiring more counselors and other student-support professionals.

Ricker said talks on a new two-year contract have been productive at times, but there’s still work to be done. The previous contract expired last summer.

District officials have said many union proposals merit discussion, including one that would open up prekindergarten slots for all district 4-year-olds.

But the district said some of the proposals aren’t affordable.

“We share core values,” said Matt Mohs, the district’s chief academic officer. “But we disagree about how to get there and what funds are available to get there.”

He said he’s not surprised the union’s leadership is considering a strike. While recent talks have been productive, key issues remain unresolved: compensation, class sizes and staffing for support and specialized positions.

St. Paul educators haven’t gone on strike since they launched the nation’s first teacher strike in 1946. They came close in 1989, but a walkout was averted at the last minute.

Under state law, the union would have to provide the district 10 days’ notice before striking.

Last week, teachers rallied in front of more than 50 schools to support the union’s proposals.

St. Paul has more than 3,000 educators, who make an average of $68,500 at the elementary level and $67,400 at the secondary level.