Britain's biggest business group is urging its members to enable millions of people to work part-time on June 23 to enable them to vote in the EU referendum.
Sky News has learnt that the CBI will write later this week to the 190,000 companies it represents to allow staff to take part of polling day off - a move that will be interpreted as a push to encourage a higher turnout by those voting for the UK to remain in the European Union.
It will be the latest intervention by the CBI in the referendum campaign, and will reflect a growing anxiety among pro-EU business leaders about polls in recent days showing growing support for Brexit.
The CBI, which has argued forcefully that the UK's economic future would be put at risk by leaving the EU, has already encouraged its members to inform staff about the implications of Brexit, which triggered a furious response from Leave campaigners.
Carolyn Fairbairn, the organisation's director general, said on Tuesday night: "The referendum on 23 June will be the biggest decision that most of us will get to vote on in our lifetimes.
"The decision on whether we choose to stay in the EU will have serious implications for our economy, jobs and the opportunities for young people in the years ahead and it’s important everyone has their say."
Ms Fairbairn added that companies had "an important role to play", and urged them to "do what they can to help their staff have the time to cast their vote".
She went on: "That might mean showing greater flexibility on when they expect employees to arrive at work and leave for the day, or perhaps see how shift patterns can be adjusted as a one-off."
Analysts believe that a low turnout on the day of the referendum represents the biggest threat to the Remain campaign, with a number of social media initiatives launched in the past week to encourage younger voters to participate.
Sky News understands that a number of employers have already agreed to allow staff to take time off on 23 June to visit polling stations.
Zoopla Property Group (ZPG), the online portal, has told its 700 employees that they can work a half-day.
Its founder and chief executive, Alex Chesterman, told Sky News: "We believe the EU referendum is one of the most important decisions in recent memory that we each have a say in and one which will likely affect all of us for many years to come.
"Given the importance of this matter, we are keen to ensure that everyone at ZPG who wishes to exercise their right to vote has the time to do so.
"That’s why we are allowing our staff of over 700 people, if they wish, to take a half day off on this day to ensure they can visit their respective polling station."
Other big employers, including Punch Taverns, are considering similar measures for staff who would otherwise face difficulty registering their vote.
Pro-Brexit campaigners said the CBI's initiative showed that the Remain camp was "clearly worried".
Matthew Elliott, Vote Leave's chief executive, said: "(It is) no surprise that the the pro-EU fanatics at the CBI are doing everything they can to try and twist the arms of the nation's employees to get them to go out and vote to keep us sending £350m a week to Brussels.
"If people want a brighter future they should Vote Leave on 23 June."
