Boris Johnson will launch the Conservative election campaign later, promising to “get Brexit done”.
The prime minister has met the Queen at Buckingham Palace, marking the official start of the election period in the run-up to the 12 December poll, BBC reported.
He is making a statement in Downing Street shortly before addressing his first rally of the five-week campaign.
But the PM is facing fresh difficulties after the resignation of the Welsh Secretary Alun Cairns.
Mr Cairns quit the cabinet after claims he knew about a former aide’s role in the “sabotage” of a rape trial.
The BBC’s assistant political editor Norman Smith said he did not expect Mr Johnson to address the cabinet minister’s resignation in his statement, saying it would “suck the life out” of his core message on Brexit and other issues.
While Mr Cairns was not a “big name” outside of Wales, our correspondent said his exit was a “major disruption” and Mr Johnson clearly “need to get a grip” of a campaign that was “on the brink of disarray”.
The resignation has compounded an already problematic start to the campaign for the party, which has seen two Tory candidates apologise for comments about victims of the Grenfell tragedy.
Party chairman James Cleverly said Jacob Rees Mogg and Andrew Bridgen’s remarks about the actions of Grenfell victims had “caused hurt and distress”, telling BBC Breakfast “we don’t always get things right and when we get it wrong we apologise”.
Elsewhere, as the starting pistol is fired on five weeks of official campaigning:
The Green Party has launched its campaign with a promise to invest £100bn a year on climate action
The Liberal Democrats have pledged to spend £2.2bn a year on mental health services, funded by a 1% rise to income tax
Tory MP Andrew Bridgen has apologised “unreservedly” for comments about the Grenfell Fire Tragedy
A senior Welsh Conservative says it looks “very difficult” for Alun Cairns to lead the party’s election campaign in Wales after his former aide “sabotaged” a rape trial.
Labour’s ruling body meets to discuss whether Chris Williamson and Keith Vaz can stand as candidates
Writing in the Daily Telegraph earlier, Mr Johnson likened the UK to a “supercar blocked in the traffic” by Brexit, adding: “If we can get Brexit done, there are hundreds of billions of pounds of investment that are just waiting to flood into this country.”
He said those in Labour “point their fingers” at the rich “with a relish and a vindictiveness not seen since Stalin persecuted the kulaks” – wealthier peasants during the Russian Revolution, many of whom were murdered or starved to death.
And he repeated his claim that as well as another referendum on Brexit, a Labour government would also lead to a second vote on Scottish independence.
