The fate of the student opportunity fund – which supports students from disadvantaged backgrounds attending university – will be decided on Thursday after a stalemate between the Treasury and the Department of Business, Innovation and Skills (Bis) over cutting the £327m fund.

The quartet of senior coalition figures – David Cameron, George Osborne, Nick Clegg and Danny Alexander – will meet to finalise how to fill the yawning Bis budget deficit, with the Treasury pushing for substantial cuts in the student opportunity fund.

Alexander, the Liberal Democrat minister who oversees departmental spending, is said by a source involved in the negotiations to favour doing away with the entire fund, over the opposition of higher education minister David Willetts and Bis secretary Vince Cable.

Willetts is understood to be worried by the plan, which needs to be resolved in order to set out the government's funding to the higher education sector. Willetts is said to be lobbying his Conservative colleagues against the cut in private, in opposition to those in the Treasury and the Cabinet Office who see the fund as ripe for cutting.

The source said the figure being discussed was not £200m, as previously suggested, but the entire £327m student opportunity allocation – previously known as the widening participation grant – which Bis pays to universities that recruit students from disadvantaged backgrounds, via the Higher Education Funding Council for England.

"Danny feels that higher education is not taking its fair share [of cuts]" the source said. "It's staggering that this is the one bit of [the BIS budget] that supports social mobility. Why would you get rid of that? It beggars belief."

The student opportunity fund is used by universities for widening access, improving retention and success rates for those from disadvantaged areas, as well as supporting disabled students. Cuts to the fund would follow an earlier £100m slashed from the national scholarship programme, another programme designed to improve social mobility in higher education.

Liam Byrne, Labour's shadow minister for higher education, said suspicions remained that the cuts were a result of the coalition struggling to fully fund its promise to expand enrolment in English universities.

"It's completely unacceptable for Britain's poorest students to pay for the dogma, deception and pure mismanagement at the Department for Business. No one can no believe a word the chancellor has said about promised new places," Byrne said.

A spokesman for the Open University said it was deeply concerned by the plans.

"Social mobility is central to the government's ambitions and the OU's mission, so it is deeply concerning to see reports that funding for students from the most disadvantaged backgrounds may be cut," he said.

"The OU is incredibly proud of its track record of helping these students realise their potential and go on to make a strong contribution to the UK economy. The prime minister and his cabinet colleagues must be careful that any spending decisions will not reduce the life chances of the most vulnerable in our society."

Under the coalition agreement between the Conservative and Liberal Democrat parliamentary parties, the quartet is the final arbiter of contested spending cuts.

Separately, a group of 30 of the largest further education colleges has written to Clegg to protest against further cuts harming the FE sector, "against a backdrop of continued uncertainty and rumour of further cuts to come in which FE will bear the brunt of overspends in other areas."

The letter from the 157 Group points out that while funding for state schools has been protected and universities have benefitted from tuition fee increases, funding for FE colleges has fallen substantially since the coalition took office.