The Tories have said they would scrap the three academic Diplomas
The number of teenagers starting the first new Diploma courses in England has slumped again to below 12,000, the government has said.
Initially it had hoped to see at least 40,000 taking the first five subjects, but said this summer that the total starting in September would be 20,264.
Now Schools Secretary Ed Balls has told MPs the number of 14 to 19-year-olds starting courses last month was 11,490.
Mr Balls announced plans for youngsters to have more say in shaping Diplomas.
He said a national 14-19 learner panel, which would give young people a key role in feeding in views that would develop national policy, would be set up by next spring.
The Diplomas are courses in industry sector subjects which mostly combine practical and theoretical learning.
They are being delivered by consortiums of schools, colleges and employers and ultimately will cover 14 employment areas, plus the academic subjects of humanities, science and languages.
Mr Balls gave the updated participation figures as he published the government's "implementation plan", Delivering 14-19 Reform: Next Steps.
A breakdown supplied to the BBC News website by the Department for Children, Schools and Families showed that 8,128 learners under 16 were studying for Diplomas, down 38% from more than 13,000 on the previous estimate, and 3,362 post-16 (down 53% from 7,096).
More than one in six - 1,998 - were reported to be on basic Level 1 courses. Only 1,416 were on Level 3 courses, equivalent to A-levels or BTec Nationals. Overall, creative and media was the most popular subject area.
The government's implementation plan included the criteria for bidding for a share of £55m to develop innovative "world class showpiece Diploma facilities" to share excellence in teaching.
Among other things Mr Balls said that the prestigious Russell and 1994 groups of universities had now said they would consider applications from students with Diplomas.
This probably overstates the case, with the Russell Group's position being that its members are still assessing the academic rigour and general suitability of the Diploma as a route to higher education.
Mr Balls said: "Young people are savvier than they are sometimes given credit for and have the ideas and energy we need to ensure the great changes we make are relevant, inspiring and demanding enough.
"In fast-changing times we need to give the next generation the power to shape their education and training because they have a vested interest in their success."
Shadow Children's Secretary Michael Gove said: "We want the Diplomas to succeed as a high quality alternative to the academic route, so it is disappointing the numbers taking up the new qualifications are so far below ministers' estimates."
He added: "Coming in the wake of the Sats fiasco and with Ed Balls currently embroiled in yet another administrative disaster over EMA payments, the confidence of parents and teachers in his department's ability to deliver large-scale projects is rapidly disappearing."
But the director of learning and quality at the Association of Colleges, Maggie Scott, said the previous figures had been based on estimates given very early in the process - as far back as November 2007.
It would have been inaccurate to suggest the figures given out by the department at the end of August had referred to those who had signed up for Diploma courses, she said.
Ms Scott added: "There were a number of messages coming through over the summer - anxieties being expressed. I don't think we have ever had a qualification that has been developed in the public spotlight like this.
"It was probably partly optimism on the part of the consortia, but it is actually quite difficult to predict what goes through the mind of a 14-year-old when they come to make their choices.
"Next time around there will be a much greater degree of realism about the number of young people who actually want to go for something that's new."
It would only have been possible to know exactly how many would be taking the Diplomas when they came to enrol in September, she said.