The Conservative leadership candidates have been urged to make a pledge to put scientific research at the heart of their economic policy.
Scientific bodies have called on Jeremy Hunt and Boris Johnson to set out their long-term plans for research.
They want them to commit to ensuring that the UK remains a world leader in research and innovation.
There is also alarm that the political uncertainty is stalling efforts to develop a strategy for UK science.
The president of the UK's Royal Society, Prof Sir Venki Ramakrishnan, told BBC News that the uncertainty "could threaten the research and innovation that are vital for the long-term health of our economy".
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Science has been relatively well-funded under Theresa May. Under her premiership, science funding has been increased by more than £2.5bn and a target has been set to boost public and private science spending to 2.4% of GDP by 2027 - which would require a further £20bn from government and £40bn from industry.
Research is also at the heart of the government's industrial strategy, which aims to develop a high-skills, high-technology economy.
Sir Venki said it was vital that both leadership candidates commit to continuing the policy.
"If we lose the momentum behind the commitment to investing 2.4% of GDP, we will be left behind by our competitors. If that happens, any talk of a bright future for the UK could have a very hollow ring to it.
"We need Boris Johnson and Jeremy Hunt to really get behind the 2.4% target, including committing to investing the government's own share, and show us what a real vision for future prosperity looks like."
The Royal Society, the Russell Group of Universities and the CBI, among others, are concerned that science is not on Jeremy Hunt's or Boris Johnson's radar. James Wilsdon, who is professor of research policy at Sheffield University, worries that the progress UK science has made might be squandered.
"Boris Johnson and Jeremy Hunt are now spraying around large and un-costed commitments to tax cuts and defence spending - with no mention so far of the importance of research, innovation and industrial strategy," he told BBC News.
"The 2.4% target requires billions of pounds of government investment, but it's hard to see where this will come from, when our economy faces so much uncertainty and the cliff-edge of a no-deal Brexit."
In a joint statement, several research and business bodies urge Hunt and Johnson to "ensure the UK remains globally competitive, delivering a strong and prosperous future for our economy and society post-Brexit".
It continues: "The evidence is clear: investment in R&D drives productivity and raises living standards, benefitting people and communities across the whole of the UK. From the great challenges of our time, including cancer, climate change, food security and caring for an ageing society, to the creation of high-skilled jobs, new businesses, and the innovations that power our NHS - UK research and innovation has real-life impact."
Dr Sarah Main, executive director of the Campaign for Science and Engineering (Case), said that the aim of the joint statement was to put the importance of scientific research in the minds of the two candidates for prime minister.
"This cross-sector letter shows how important it is for the next prime minister to back the UK's strength in science. It will stimulate the ideas, innovation and investment to improve the quality of life and attract global attention," she said.
Uncertainty about the level of funding for science has made it difficult for the recently created UK Research and Innovation agency (UKRI), which is the body that funds research, to develop a long-term strategy for UK science. Its plan should have been published this month.
Prof Wilsdon said that UKRI was waiting for clarity on policy before producing its plan.
"With so much political, economic and sectoral uncertainty, it's not surprising that UKRI hasn't yet published the longer-term blueprint for research and innovation that was expected. For good or ill, UKRI has pinned its strategic colours to the 2.4% of GDP mast. But choppy waters lie ahead. and if the 2.4% target goes down, UKRI may also flounder in delivering on the aspirations that surrounded its creation."
The agency's sense of paralysis has been compounded by the departure of senior staff. Its strategy director, Rebecca Endean - who joined in March 2017 - left last week, while the chief finance officer, Ian Kenyon, is due to leave in July after just over a year-and-a-half in the post. In a statement issued in April, he said it was "in light of changes within the finance and operations portfolio".
The joint statement has been signed by the Academy of Medical Sciences, the Association of Medical Research Charities, the British Academy, the Campaign for Science and Engineering, Cancer Research UK, the Confederation for British Industry, the Institute of Physics, the Royal Society, the Royal Academy of Engineering, the Russell Group and Universities UK.
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