In the minutes before school bells rang Thursday, teachers across Philadelphia and the United States gathered to underscore the importance of public education.

At Spring Garden Elementary, parents, students, and educators were joined by a visitor: Sen. Tim Kaine, the Democratic vice presidential nominee.

Flanked by Philadelphia Federation of Teachers president Jerry Jordan and national teachers' union chief Randi Weingarten, Kaine was hailed as a schools champion with bona fides. He sent his three children to public schools, his wife was Virginia's education secretary, and as mayor of Richmond, Va., Kaine visited at least one school a week to remind himself of the ground-floor effects of policy decisions.

The work "is really important to me," said Kaine, who talked up running mate Hillary Clinton's education platform, which emphasizes better support for teachers, rebuilding school infrastructure, and getting more computer-science courses in classrooms.

The "walk-ins" for education took on special resonance in Philadelphia, where educators have gone three years without a new contract.

Jordan noted that Thursday was the second anniversary of the School Reform Commission's attempt to cancel the teachers' contract. That action was ruled illegal in August by the Pennsylvania Supreme Court.

No contract talks have been held since June, and none are scheduled.

"And still, teachers and other employees have continued to make great sacrifices," Jordan said. "They have waited much too long for a contract."

At Widener Memorial School on Olney Avenue, several dozen people rallied for teachers.

Dave Malone, who has taught disabled students at the school for 12 years, said teachers are tired.

"We are being squeezed into nonexistence," Malone said. "We deserve a fair contract."

Years of budget cuts mean that Philadelphia educators are spread thin, and the lack of a contract compounds the problem. Widener, he said, has lost strong teachers because of the uncertainty.

"No one thinks they're going to become a millionaire," he said, "but we do have to live."

That Philadelphia teachers have gone more than 1,000 days without a contract is startling, said Weingarten, a frequent visitor to Philadelphia.

"If Detroit can find something for its teachers, a city like Philadelphia can find it," she said.

Weingarten said it was time for action.

"I'm hoping," she said, "that the mayor will get involved."

Kaine kept his eye on national policy and zinging Republican presidential candidate Donald Trump, and did not address the Philadelphia situation.

But he did have a warm smile for Spring Garden eighth grader Kyla Seawright, who said she has been taught by teachers who "do much more than they are obligated to do."

"It's a treat," Kaine said, "to be here at Spring Garden."