Jeremy Corbyn will continue his election-style summer campaign with visits to two Conservative-held seats on the south coast over the weekend.
The Labour leader will tell supporters in Southampton and Bournemouth on Saturday that Theresa May is at the head of a "zombie Government" and should step aside to make way for Labour's "government in waiting".
Mr Corbyn will visit Labour's top target seat Southampton Itchen, which the party held from 1992 to 2015 and came within 31 votes of regaining last month.
And he will meet supporters in the far more ambitious goal of Bournemouth West, which has been Conservative since its creation in 1950 but saw a 6.6% swing to Labour cut the Tory majority almost in half in June.
Long seen as an impregnable Tory stronghold, the constituency is now 117th on Labour's target list.
Speaking to a rally in Southampton, the Labour leader will say he hopes to win Itchen at the next election "whenever it is called".
He will say: "Theresa May's Government, propped up by the DUP, is nothing more than a zombie Government; with no ideas, no answers and no leadership. This is a Government in name only, having to ask other parties to 'clarify and improve' its policies and delaying most parliamentary business until the autumn.
"If the Conservatives are unable to govern, they should step aside. Labour is no longer just the official opposition, we are a government in waiting.
"The Conservatives' programme is in tatters following the public verdict at the General Election. Theresa May does not have a mandate for continued cuts to our schools, hospitals, police and other vital public services or for a race-to-the-bottom Brexit.
"Labour will fight these policies every step of the way, that make life worse for the many to maintain the privilege of the few."
Mr Corbyn has this month already visited the Conservative marginals of Hastings & Rye, Hendon and Chingford & Woodford Green in a bid to take the fight into Tory territory in preparation for an election which Labour strategists believe could come much earlier than the scheduled date of 2022.