It was supposed to standardise what US children were taught in schools across all 50 states, but the Common Core is now at risk of unravelling altogether.

On Monday last week, Indiana became the first state to formally abandon the education benchmarks, despite being one of the first to adopt the measures back in 2010. For many opponents, the decision sounded the death knell for the programme, which was intended to spell out what students should know and by what age.

In essence, the Common Core State Standards, as they are officially known, are America’s first tentative steps towards something similar to England’s national curriculum.

Until last week, 45 states were committed to using the standards. Then Indiana, which had complained that they allowed for “minimal input” from local educators, voted to implement its own curriculum that was not overtly “nationalised”.

This decision is merely the tip of a very large iceberg, with around a dozen further states considering dropping the standards or considerably watering them down. Meanwhile, opposition groups are finding traction in states spanning from New York to Washington and Alabama to Wyoming.

On Tuesday last week, the day after the Indiana vote, Randi Weingarten, president of the American Federation of Teachers, one of the largest teaching unions in the country, warned that the Common Core “may actually fail”.

Speaking to New York magazine Salon, Ms Weingarten said the implementation of the Common Core had been “worse than.Obamacare”, in reference to the US president’s highly controversial health-care reforms. “Between austerity and the lack of thoughtful implementation, you see that the Common Core may actually fail,” she added, “because it’s been implemented so badly in so many places, and because of the opposition from the Right and the opposition to testing.”

According to Dylan Wiliam, emeritus professor at the University of London’s Institute of Education, who sat on the Common Core validation panel, the problem is that the programme’s detractors come from across the spectrum.

“On one side you have the right wing, effectively Confederates who still can’t come to terms [with the fact that] they lost the civil war and see the standards as being pushed by the feds in [Washington] DC,” Professor Wiliam told TES. “And on the other side you have the unions, which, understandably, are concerned the tests that are aligned to the new standards will be used to evaluate their own performance.”

Their fears would appear to be warranted, given that in New York last year students across the board performed well below expected levels in the new Common Core-aligned state tests. Should this situation be repeated, teachers could lose their jobs.

The bungled introduction of the standards in New York has been seen as a warning sign for the rest of the country. Linking the measures to a whole new set of tests has caused outcry, with the directors of the New York State United Teachers union pulling their support for the Common Core earlier this year.

Unlike most other countries, the US uses its tests primarily to evaluate individual teachers rather than students, and there is huge concern among unions that the Common Core tests will have high-stakes consequences attached to them.

The country’s largest union, the National Education Association (NEA), has waded into the row, calling for a “course correction” on the Common Core.

“In far too many states, implementation has been completely botched,” NEA president Dennis Van Roekel said in a statement. “Seven of 10 teachers believe that implementation of the standards is going poorly in their schools. Worse yet, teachers report that there has been little to no attempt to allow educators to share what’s needed to get implementation right.”

Mr Van Roekel added that although his union’s members supported the “worthy goals” of the standards, there needed to be “an equal commitment to common-sense implementation”.

But while opposition to the Common Core has led to strange bedfellows, so too has support for the standards, with President Obama, Jeb Bush, who is in contention to run as the Republican presidential candidate, and Microsoft co-founder Bill Gates coming out in favour. The latter said he was “disappointed that its implementation is at risk in some states”.

The troubled beginnings of the Common Core, despite years of planning, have left onlookers at a loss when predicting how its future might pan out.

“There’s always a risk [of it unravelling],” Professor Wiliam said. “The whole thing has gone very pear-shaped very quickly. But I think it will survive, just in a watered-down form.”