Classes have been canceled in one of Colorado’s largest school districts Thursday due to a “labor shortage,” as educators will skip school to rally at the state capitol for better education funding.

The Jefferson County school teachers are using leave time to cover their absences. But if they were striking, they’d face fines and up to six months in jail, under legislation proposed by two Colorado Republican state lawmakers. The teachers will be joined by teachers from Douglas County schools, the state’s third largest school district, which will also close Thursday. On Friday, teachers from Denver Public Schools, the state’s largest district, will lead teachers from other districts in protesting. Administrators at those school districts have canceled Friday classes.

The bill, introduced in the Republican-controlled Colorado senate, has almost no chance of becoming law, due to opposition from Democrats in Colorado’s house and governor’s office. The proposal to imprison educators is getting national attention in the wake of teacher walkouts and strikes across the United States to protest low pay and substandard working conditions and benefits.

The proposed Colorado law, the “Prohibition of Strikes by Public School Teachers” act, states that “every public school teacher and every teacher organization is prohibited from directly or indirectly inducing, instigating, encouraging, authorizing, ratifying, or participating in a strike against any public school employer.”

The legislation authorizes public schools to seek a court injunction if a teacher strike occurs. Along with possible jail time and fines, teachers who fail to comply with a court order could immediately lose their jobs, according to the bill.

“I started thinking about the bill when I saw the news about teacher strikes in West Virginia,” state Sen. Bob Gardner, a Colorado Springs Republican who sponsored the bill, told the Denver Post. “It’s a wise thing to do, in some shape or form, in the state of Colorado because we have one district that’s already voted to strike. We have others discussing a strike. Strikes are not good for children.”

Another sponsor, state Sen. Paul Lundeen (R-Monument), backed off his own bill Tuesday, stating on his blog, “I would never penalize a teacher. SB18-264 was a work in progress. While I supported the idea that union-led strikes harm students and should be discouraged, it always was my intention to amend the Senate bill to remove any penalties for teachers once the bill came to me in the House.”

Colorado ranks in the lower third of states in pay for teachers and school funding. Budget shortages have forced about half of Colorado’s public school districts, mostly in rural areas, to offer a four-day-per-week schedule of classes.

Colorado teachers rallied last week against cuts in benefits to the state pension program, which covers public school workers. The state legislature is debating how to shore up the pension system, which could become insolvent if a recession hits. Ideas on the table include spending more tax money, cutting benefits, adding private retirement savings options, raising worker contributions, and more.

Education spending by Colorado’s government is constrained by a tangle of constitutional amendments that reduce lawmakers’ ability to raise and spend taxes.

Chief among the obstacles is the 1992 Taxpayer Bill of Rights (TABOR), which requires any tax increase to be approved by voters, who last rejected a statewide education boost in 2013. A measure to increase education funding by increasing corporate and income taxes by $1.6 billion could be included on November’s ballot.

School funding problems hit the state hard in 2009 after the Great Recession. Since then, state public schools have received billions less than what they should have received under Amendment 23, a constitutional amendment passed in 2000 meant to bolster school investment after state legislators slashed education spending throughout the 1990s. This year the shortfall is $828 million, according to Chalkbeat.

Colorado’s teacher protests came in response to a national wave of demonstrations by educators, like those in West Virginia, where lawmakers have failed to fund education while directing tax dollars to the wealthy.

A teachers strike in New Jersey was quickly resolved in March, and teachers in Arizona could walk out Thursday, protesting years of underfunding education. West Virginia lawmakers in March refused to raise taxes on oil and gas giants after educators staged a wildcat strike after a decade of cuts to education investment.

Teachers appear to have the support of the wider public, with a recent poll showing that 78 percent of adults in the United States think teachers are underpaid.