Work to save the Staffordshire Hoard is an example of collaboration
Art collections held by local authority museums are in danger of falling behind those of national attractions, the Art Fund has warned.
The charity found that 75% of the 276 UK museums it polled cited inadequate funding and reduced spending as the biggest barrier to collecting.
Some 60% said avoiding post-election cuts was their biggest challenge.
The Collecting Challenge 2010 survey found 14% of local authorities saw adding to collections as a priority.
The survey found one in five museums and galleries felt avoiding staff cuts, and therefore loss of expertise, was a major obstacle to amassing more items.
The charity said survey responses suggested museums were "nervous" about public money being cut further after the general election.
It found museums are finding innovative ways to enrich their collections.
For example, some 47% of museums and galleries are displaying an increasing number of items borrowed from other institutions, and 59% expect this trend to rise.
And 11% of museums have seen an increase in joint acquisitions in the last five years and 20% expect further combined purchases to be made in future.
Stephen Deuchar, director of the Art Fund, said: "The loss of curatorial knowledge from museums is deeply troubling.
"We must do all we can to preserve these skills now for the benefit of future generations of museum-goers."
Mr Deuchar said museums are "right to be concerned about the possibility of core funding being reduced after the election".
"Without a clear sign that funding will be maintained, collecting, whether individually or collectively, could become a rare luxury for museums," he said.
Mr Deuchar pointed to the recent work to save the Staffordshire Anglo-Saxon hoard as a good example of collaboration.