By Alison Smith
BBC News education reporter, at the ATL conference
Mr Garner dismissed the plan of School Secretary Ed Balls
Proposals to fast track former bankers through teacher training courses in six months are "demeaning" to the profession, a teaching union says.
At the Association of Teachers and Lecturers annual conference, members unanimously voted to resist the idea.
Teachers said the idea was "wrongly advised and ill-motivated" and pupils would get a "third-rate education".
But the government said only the most able candidates would be eligible to train in six months.
Andy Garner, a teacher from Calderdale who proposed the motion, ridiculed the prime minister and key cabinet members, portraying them as desperately searching for ideas to bring down unemployment.
Perhaps the government thought helping bankers into teacher training would achieve their goal of getting half of young people into university, he suggested.
To former finance workers wishing to become teachers, he said: "It's a good job you are used to redundancies, because redundancies are rife in teaching.
"If you really think you want to become a teacher, why not spend a year working as a teaching assistant, if you can find a job, and find out if it really suits you?"
He said anybody who trained to be a teacher within six months would be akin to a police community support officer - "respected, but not quite there".
Former ATL president Julia Neal said nobody would want their children to be taught by poorly-trained teachers.
"Teachers need time to prepare and understand child development, and need to understand the history and philosophy of education as well as having experience of carefully prepared structured practice," she said
"Saying it can be made intensive means rushing it and giving children a third-rate education."
Teachers said the move did not fit with the decision by the Department for Children, Schools and Families to make teaching a Masters-trained profession.
All the evidence was that teachers ought to train for a longer period rather than a shorter one, they said.
When the scheme was announced last month, ATL general secretary Mary Bousted called it "back of a fag packet stuff".
The National Union of Teachers also expressed its concern.
As part of the initiatives announced, 200 people seen as future head teachers will also be able to move into school leadership within four years, via an accelerated headship programme.
Schools minister Jim Knight said: "By cutting the initial teacher training course to six months for the most able candidates, we will make teaching a more attractive choice for experienced people who want to get into the classroom quickly but need high quality initial teacher training."
A spokeswoman for the DCSF added: "No child will receive a third rate education. This is only for the very best; all candidates will be rigorously assessed before they are accepted to start training to see if they have the aptitude, appetite and experience for teaching and managing children, and the motivation needed to take a very intensive course.
"The Training and Development Agency will devise an intensive programme, including some form of training period before the trainees start in schools, and extra training over and above what would be available on a normal GTP.
"Trainees will only pass when they can demonstrate that they meet the same Qualified Teacher Status standards as all teachers have to meet. We are surprised that a union would not welcome the best graduates and people with real industry experience who can inspire young minds into the teaching profession."
Graham Holley, chief executive of the Training and Development Agency for Schools, said: "We welcome this new route into teacher training.
"We will work with initial teacher training providers to ensure that high quality provision is available to those who want to achieve qualified teacher status faster than on conventional PGCE (postgraduate certificate of education) courses."