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.

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