Mr Patten told the annual assembly of the moderate Association of Teachers and Lecturers in Cardiff that a review would consider slimming the curriculum and simplifying testing.
But he insisted that this summer's tests for 14-year-olds will go ahead.
Last night leaders of the association withdrew their opposition to a ballot on testing, paving the way for members to join the other unions in fighting Mr Patten. They will debate a boycott this morning.
Peter Smith, the general secretary, said: ' Mr Patten has offered no solutions to this year's problems.' He predicted a 'knife-edge' debate on the boycott.
Executive members were said to be angry that Mr Patten had said on television that his reception at the conference as warm. They said it was merely courteous. Mr Smith said it would be wrong for Mr Patten to assume that all parents would be on his side.
Of two other big teachers' unions, the National Association of Schoolmasters Union of Women Teachers is already boycotting national curriculum testing and assessment, and the National Union of Teachers is expected to back a boycott at its conference this weekend. They both criticised the speech, saying that Mr Patten had admitted this year's tests were flawed, and he should therefore call them off.
The three unions have more than 300,000 members. Even if just two of them agree to a boycott the tests for 14-year-olds in English, maths, science and technology will have to be called off in many schools.
Ministers' best hope of avoiding disruption in schools this summer lies in the courts. An appeal by Wandsworth council in south London against a High Court ruling that the NAS/UWT boycott is lawful is due to be heard on 20 April.
Mr Patten told the conference that he had written to Sir Ron Dearing, chairman of the new School Curriculum and Assessment Authority, asking him to concentrate first on slimming down English and technology, which were already under review. Other subjects would follow.
He said he was also asking Sir Ron to examine the success of the 10-point scale on which children's achievements are measured.
David Hart, general secretary of the National Association of Headteachers, said the speech was a modest step in the right direction but warned Mr Patten he would face a boycott next year as well as this unless he carried out a thorough review of testing.
Nigel de Gruchy, general secretary of NASUWT, said: 'To promise an urgent review some time next year is a contradiction in terms.'
Mr Patten said a boycott would prevent the development of simpler tests because there would be no evidence on which to base improvements.
A boycott would not be good for pupils: 'It will mean this year's 14- year-olds lose the only opportunity they have to be formally tested against national standards before taking GCSEs. It will do nothing to enhance the professionalism of teachers in the eyes of parents or the public.'
The need for testing was reinforced, he argued, by evidence that a higher proportion of young people left school without good basic skills in maths, science and English than in competitor nations.
Outside the conference Mr Patten denied the tests were flawed.
Doug McAvoy, general secretary of the NUT, said: 'There is nothing new in what he is saying. What he has done is to emphasise the flawed nature of these tests. They should not be used to judge schools or pupils.'
Asked whether she supported a boycott, Ann Taylor, Labour's education spokeswoman, said: 'I would support an attempt to get the Secretary of State to change his mind.' She predicted the tests would collapse.Reuse content