Nigel Farage has insisted he won't be "too far away from the action" and will put pressure on Boris Johnson to ensure he gets Brexit done.
The Conservative leader won an 80-seat majority at the general election and the prime minister said his party won an “overwhelming mandate… to get Brexit done and we will honour that mandate by 31 January”.
Mr Farage's Brexit Party, who took in 275 seats and 2 per cent of the overall vote but returned no MPs, admitted pressure from his party was squeezed by the Conservatives.
However Mr Farage insisted he would "not too far away from the action", and that pressure would soon intensify if the prime minister failed to live up to his promise to get Brexit done.
He added he was now concerned with what form Britain's exit from the EU would look like, rather than if Brexit would still happen.
He wrote: “The truth is that the threat from the Brexit Party, together with the influence of the European Research Group (ERG) in parliament, has disappeared for the time being.
“Questions over the future shape of Brexit and Britain’s place in the world are now entirely in the hands of Johnson.
“With half of his Cabinet having voted Remain, and substantial global pressures on him, it will be tempting for him to pursue the easy option of a soft Brexit.”
The former Ukip leader, who did not stand at the General Election, added that he thought his work had been completed in June 2016 when 51.8% of voters opted to Leave.
He said: “Having endured three elections in the last 30 months, let us hope the country can look forward to a prolonged period of political stability and certainty.
“Whatever happens over the coming months, I will make sure I am not too far away from the action. The fact is that if Brexit does not ‘get done’, as Johnson has promised repeatedly over the last six weeks, pressure will have to be reapplied.”