More than a quarter of young voters are not on the electoral roll with just 10 days until the deadline to register, new figures show.
Figures from credit checking firm ClearScore show that 26 per cent of under 24s are not registered.
Registration for the June election closes on 22 May, but an estimated 1.3m young people are currently likely to be unable to vote.
Appealing to younger voters has been a repeated issue in recent political campaigns.
Despite being broadly more pro-Europe than other voters, research has indicated that millennials voted in smaller numbers than expected in the Brexit referendum.
However, Equifax, another credit information specialist, has estimated the electoral roll is 1.8 per cent, or 835,701 people, larger than at the 2015 General Election.
Lisa Hardstaff, Equifax credit information expert said: “This suggests a greater level of political engagement in the last twelve months, perhaps prompted by last year’s European Union referendum.”