"The problem that we have got is that we cannot at the moment have any confidence in Boris Johnson abiding by any commitment or deal that we could construct", he told the BBC.
This week, 21 Conservative MPs were expelled from the party for voting to block a no-deal Brexit.
"Huge numbers of his constituents are horrified", said David Keys from the European Movement, who is gathering hundreds of signatures from constituents for a letter warning Johnson that he will lose their support in the next election over his approach to Brexit.
Jo Johnson - who shares his brother's prominent blond hair - also said he will step down from Parliament rather than compete at the next election.
They've declared effectively that the 31st of October is the ultimate deadline and they'll be no extension and if Boris Johnson doesn't achieve that, then he'll need to go to an election and acquire a mandate from the voters to continue on his Brexit path.
Boris Johnson suffered another hugely damaging blow to his premiership and authority after his brother quit his role in the Cabinet accusing the Prime Minister of not acting in the national interest.
Richard Tice, who also represents the Brexit Party in Strasbourg as an MEP, issued the stark warning to Johnson on Thursday via social media.
A general election could come on October 15, and the surge in registrations comes weeks ahead of the September 27 deadline.
Labour Party politicians and pro-democracy groups celebrated Wednesday as more than 100,000 people reportedly registered to vote in a 48-hour period this week amid mounting chaos in the United Kingdom government in anticipation of a possible general election in October.
A spokesperson for the prime minister said his speech would make the case that "it is now time for the people to decide after Parliament has failed them, so we can resolve this once and for all".
The opposition Labour Party cast Johnson's language - including calling Corbyn a "chicken" - as pathetic, said he was trying to act like U.S. President Donald Trump, and compared him to a 3-year-old toddler having a tantrum.
The pound gained 0.3% to $1.2295, after rallying 1.4% on Wednesday. That margin halved in the 2017 general election, and losing his seat in a possible snap poll next month would mean a swift end to his short premiership.
Johnson, the face of the 2016 Vote Leave campaign, has pushed for an election on October 15, two weeks before the United Kingdom is due to leave the European Union, though opposition parties are debating which date they would accept. "I think it's a no-brainer".
But early Thursday, the Lords agreed to let the bill pass through the chamber by Friday, allowing it to become law on Monday.