David Triesman, general secretary of the Association of University Teachers, offered the deal in the hope of making the AUT the single HE union.
In return Mr Triesman is offering NATFHE a package of contracts and support. NATFHE, which represents academic staff in the new universities and colleges of higher education as well as FE colleges, has debts which may hit pound;800,000 this year.
Mr Triesman insists that a full AUT-NATFHE merger was not on the cards. Instead he hopes two specialised unions will be created - an expanded AUT for all HE staff and a NATFHE focused on FE.
Its new general secretary Paul Mackney has already ruled out any transfer of members to the AUT, arguing the move towards a more flexible education system will create the need for a union encompassing both further and higher education.
Talks between the two unions resumed last month after the election of Mr Mackney as NATFHE's general secretary. Long-running discussions on the future of relations between the two bodies were put on ice after the departure of previous NATFHE leader John Akker last spring.
Mr Mackney has already offered not to stand in the way of a merger between the two bodies. NATFHE official policy is to push for the creation of a single union for lecturers. AUT policy is subtly, but crucially, different: to create a single union for higher education.
Mr Triesman told The TES the AUT's position as a "classical craft union" had been the key to its success. The union has resisted the expansion of lecturing agencies into higher education - although not the invasion of short-term contracts. The AUT leadership is even considering its own recruitment agency, designed as a clearing house for academic jobs, to keep the threat at bay.
Mr Triesman said: "The AUT has been growing quite considerably. I would like to think that it's about a particular style of approach which is a real focus on higher education issues; being really specialised.
"I think there are some important similarities between people doing different teaching post-school, but there are some incredibly important differences. They do not diminish the importance of further education and what it can do."Mr Triesman predicted that higher education staff would drift to the AUT from NATFHE, but said agreement to separate higher and further education unions would provide a better way forward.
Any move to reorganise the two unions would be accompanied by closer ties between them, perhaps through a multi-union council, to help co-ordinate approaches to ministers or share expertise.
He acknowledged that the role of lecturers may change under the Government's policy of promoting lifelong learning. But he said: "A massive blurring of the differences between higher and further education would have to happen. Now I don't think it's going to happen."
Mr Mackney said nothing was being ruled out at this stage. He said: "I really think there's a historic opportunity for professional unity, but if the AUT don't want it, we are on for other kinds of co-operation.
"You could have one union for lecturers, with independence for higher and further education wings, or you could have two unions. But you could also have federation or other sorts of arrangements. But I really think the AUT should think very seriously about this."