When 30,000 Los Angeles teachers went on strike on Monday, prominent Democrats — and potential presidential candidates — lined up to give their blessings.

Senator Kamala Harris of California said she was “standing in solidarity” with teachers, who are demanding higher pay, smaller classes and more support staff.

“I’m with teachers all the way,” Senator Elizabeth Warren of Massachusetts said on Twitter.

Senators Cory Booker, Sherrod Brown, Kirsten Gillibrand and Bernie Sanders all shared similar sentiments about a strike that has drawn broad public support but disrupted the routines of half a million, mostly low-income children.

In 2019, after a year of teacher walkouts across the country, it is practically impossible for a national Democrat to profess anything short of full-throated support for picketing educators. But many of them this week steered clear of the most contentious underlying cause of the strike: the teacher union’s opposition to the growth of charter schools, and the union’s claim that district officials — who are largely Democrats — favor charter schools over traditional ones.