The optimism of UK businesses reached its lowest level since 2012 last month, falling by 0.67 points to 95.59.
This is just about the 95 level which indicates zero growth, said business advisory firm BDO, which carried out the research.
According to its latest Optimism Index, the manufacturing and services sectors reported the biggest drops in confidence, having plummeted by 3.38 and 0.34 points respectively.
It comes after a “tough” month for businesses, which were hit by ongoing political and economic uncertainty as well as poor weather conditions.
BDO partner Peter Hemington said: “The last time we saw business confidence at such a low level was when the country was staggering out of the doldrums caused by the global financial crisis.
“With an unpredictable general election looming, continued political volatility in the UK remains a key driver of falling optimism.
“Given British businesses are telling us that new hires and investment are hard to justify at the moment, growth will continue to remain elusive until there is some kind of resolution of the Brexit conundrum.”