According to Corbyn’s office, he plans to say the party is “on the threshold of power” in a speech he is slated to give to the party’s annual conference on Wednesday.
Despite reducing Prime Minister Theresa May’s Conservatives to a minority administration in June’s snap election, the party remains divided over Europe.
Some of the members seek to keep Britain inside the bloc’s single market, while Corbyn is cool to the notion.
He will accuse government ministers of “bungling” Brexit negotiations and call on May’s government to “pull yourself together or make way” for others to be able to negotiate the UK’s exit from of the bloc.
One of the Labour leader’s closest shadow cabinet allies, Angela Rayner, told Sky News that Corbyn has proved he is “prime minister material” and that he would be able to “run Britain and run the economy better than Theresa May.”
Meanwhile, President of the European Council Donald Tusk said Tuesday that “no sufficient progress” has been made to move to the next phase of Brexit talks in Brussels.
EU and UK officials are holding a fourth round of Brexit negotiations this week in Brussels which has seen little progress so far.
The negotiations started on Monday in Brussels, where the EU’s chief negotiator Michel Barnier insisted that he would not discuss May’s call for a two-year transition deal until there was progress on the other issues.
The European Council will decide in October whether sufficient progress has been made to begin trade talks, as the UK wants.