Seizing on a national anxiety over poor student performance, many governors are taking aim at a bedrock tradition of public schools: teacher tenure.
The momentum began over a year ago with President Obama's call to measure and reward effective teaching, a challenge he repeated in last week's State of the Union address.
Now several Republican governors have concluded that removing ineffective teachers requires undoing the century-old protections of tenure.
Governors in Florida, Idaho, Indiana, Nevada and New Jersey have called for the elimination or dismantling of tenure. As state legislatures convene this winter, anti-tenure bills are being written in those states and others. Their chances of passing have risen because of crushing state budget deficits that have put teachers' unions on the defensive.
"It's practically impossible to remove an underperforming teacher under the system we have now," said Gov. Brian Sandoval of Nevada, lamenting that his state has the lowest high school graduation rate in the nation.
Eliminating tenure, Mr. Sandoval said, would allow school districts to dismiss teachers based on competence, not seniority, in the event of layoffs.
Politics also play a role.
"These new Republican governors are all trying to outreform one another," said Michael Petrilli, an education official under President George W. Bush.
In New York City, Mayor Michael R. Bloomberg has campaigned aggressively for the state to end "last in, first out" protections for teachers. Warning that thousands of young educators face layoffs, Mr. Bloomberg is demanding that Gov. Andrew M. Cuomo scrap the seniority law if the budget he will unveil Tuesday includes state cuts to education.
Teachers' unions have responded to the assault on the status quo by arguing that all the ire directed at bad teachers distorts the issue.
"Why aren't governors standing up and saying, ‘In our state, we'll devise a system where nobody will ever get into a classroom who isn't competent'?" said Dennis Van Roekel, president of the National Education Association. "Instead they are saying, ‘Let's make it easy to fire teachers.' That's the wrong goal."
Tenure laws were originally passed - New Jersey was first in 1909 - to protect teachers from being fired because of race, sex, political views or cronyism.
Public-school teachers typically earn tenure after two or three years on probation. Once they receive it, they have a right to due-process hearings before dismissal, which in many districts makes it expensive and time-consuming to fire teachers considered ineffective. Tenure also brings seniority protections in many districts.
In recent years, research on the importance of teacher quality has sparked a movement to evaluate teachers on how well students are learning - with implications that undermine tenure.
The movement gained momentum with the Obama administration's Race to the Top grant contest last year. Eleven states enacted laws to link student achievement to teacher evaluations and, in some cases, to pay and job security, according to the American Enterprise Institute.
Now some politicians and policy makers have concluded that if teachers owe their jobs to professional performance, then tenure protections are obsolete.
The former school chancellor of Washington, D.C., Michelle Rhee, who campaigned against tenure as early as 2007, has made abolishing it a cornerstone of a new advocacy group, Students First, which has advised the governors of Florida, Nevada and New Jersey.
All are Republicans, but Ms. Rhee, a Democrat, insisted that the movement was bipartisan.
"There's a willingness to confront these issues that has never before been in play," she said, noting that some influential Democratic mayors, including Cory A. Booker in Newark and Antonio R. Villaraigosa in Los Angeles, have also called for making it easier to dismiss ineffective teachers.
In a speech in December, Mr. Villaraigosa - who once worked as a teachers union organizer - said, "Tenure and seniority must be reformed or we will be left with only one option: eliminating it entirely."
The two national teachers' unions insist that they, too, favor some degree of reform. The American Federation of Teachers endorsed a sweeping law in Colorado last year that lets administrators remove even tenured teachers who are consistently rated as ineffective.
Many teachers who accept linking job security to their effectiveness still want to require administrators to present any evidence against them in a hearing, which critics of tenure like Ms. Rhee say is unnecessary.
Ada Beth Cutler, dean of the education college at Montclair State University in New Jersey, said, "One of the fears I hear from teachers is that in these tough budget times, what's going to stop someone from firing someone at the top of the pay scale?"
Mr. Van Roekel of the National Education Association labels tenure laws "fair dismissal laws" that protect from arbitrary firing.
"In all my years in education I don't remember a time when there was this much concerted effort to eliminate fair dismissal laws," he said.
In New Jersey, Gov. Chris Christie, whose combativeness with the teachers' union has buoyed his national reputation, appears to have a good chance of getting a bill from the Democratic-controlled Legislature that reshapes tenure.
Under a pair of bills moving through the Indiana General Assembly, teachers would have to earn "professional" status based on evaluations tied to student learning, and their collective bargaining would be limited to salary, not seniority rules.
"Most of these reforms would have been dead on arrival" last year, said Tony Bennett, the Indiana superintendent of public instruction.
Gov. Mitch Daniels of Indiana has said that "teachers should have tenure," but the bills introduced by his fellow Republicans call for teachers' traditional protections to be sharply reduced.
It is similar in Florida, where lawmakers plan to reprise an anti-tenure bill from last year that provoked such an outpouring from teachers that the moderate Republican governor, Charlie Crist, vetoed it.
That is unlikely under the new Republican governor, Rick Scott, who told the Greater Miami Chamber of Commerce last month: "Good teachers know they don't need tenure. There is no reason to have it except to protect those that don't perform as they should."
And in Idaho, Gov. C. L. Otter, a Republican, presented an education plan last month that said bluntly, "The state will phase out tenure."
Idaho's schools superintendent, Tom Luna, argued that the plan would not subject teachers to arbitrary dismissal.
Mr. Van Roekel of the teachers' union disagreed. Recounting a story that had the burnish of something told many times, he recalled that around 1980, when he was a union leader in Arizona, he had arranged to have a speech pathologist assess a teacher whom a principal was trying to fire because of a speech impediment. The pathologist determined that the teacher had a New York accent.
"She would say ‘ideer,' instead of ‘idea,' " Mr. Van Roekel said. "The principal thought that was a speech impediment. Without a fair dismissal law, that principal could have fired her arbitrarily, without citing any reason."