Exam experts have warned that the national reference test, a key aspect of forthcoming GCSE reform, is in trouble and will not work as intended.

TES has learned that the deadline for awarding a contract to run the test, which is designed to help set national GCSE standards, has been missed. At least three major assessment organisations that were thinking of bidding for the project - in which thousands of Year 11 students would be expected to take extra maths and English tests in the run-up to their GCSEs - have decided to opt out.

Concern has been voiced that exams regulator Ofqual is being overly ambitious and has not allowed enough time for the new test, due to be sat from 2017, to be properly developed.

Ofqual is planning to use the national reference test (NRT) as a guide on whether to allow GCSE grades to increase or not. Without the test it is unlikely that grades will rise above previous years’ levels, because of the regulator’s controversial “comparable outcomes” approach to tackling grade inflation.

But exam industry insiders are claiming that the watchdog has failed to appreciate the technical difficulties involved. One told TES that the NRT would be a reasonable tool for helping to monitor standards, but using it to set precise GCSE grade boundaries would not work.

“Is it going to be a useful bit of information to put into the overall pot in terms of determining GCSE standards? Yes, it will be useful,” the insider said. “Will it be the single definitive point which will enable you to decide whether the cut score [grade boundary] in GCSE maths should be 62 or 64? No. But the contract is written as if it would.”

Serious problems with the NRT would be another big blow to Ofqual, which had to ask ministers for extra funding to pursue the idea. The regulator is already under huge pressure, with Nicky Morgan this week criticising its plans to remove science practicals from GCSE and A-level grading. Sources close to the education secretary have also accused Ofqual of failing to do enough to prevent a “race to the bottom” on GCSE maths standards.

The deadline for awarding the NRT contract has been missed despite having been extended from August 2014 to the end of last year.

TES understands that Pearson, Cambridge Assessment and Durham University’s Centre for Evaluation and Monitoring considered bidding but have decided not to. Concerns have been raised that the contract would “punish” a contractor that failed to set up the tests in a substantial proportion of England’s secondaries in “double-quick time”.

Ofqual has said that it could use the NRT in GCSE grading from 2018, but exam experts argue that this would not allow for the years of piloting that such an approach requires.

Some organisations have been opposed from the outset. Responding to Ofqual’s April 2014 consultation on the use of an NRT in GCSE grading, the Royal Statistical Society said it “strongly” disagreed with the idea. Exam board AQA was also against the scheme, questioning whether NRT results would be accurate enough.

Ofqual said its tendering process for the NRT was confidential and it would not comment until it was concluded.