Theresa May and Boris Johnson are said to be at war over Brexit as the Conservative party conference begins.
Mr Johnson branded her Chequers plan deranged and preposterous, in an interview with the Sunday Times published on the morning the conference is to begin.
In remarks that will fuel speculation about his leadership ambitions, he attempted to make a distinction between himself and Mrs May, saying: Unlike the Prime Minister, I campaigned for Brexit.
He once again refused to say if he plans to launch a leadership campaign against Mrs May.
The prime minister said she is going to serve for as long as the party wants her, and I certainly think she should, he added.
Meanwhile the PM used her own interview with the Sunday Times to set out the political agenda she will be announcing at the conference in Birmingham this week.
Under her plans, people and businesses who do not pay tax in Britain will face a surcharge of between 1% and 3% when they buy a property, with the money funding measures to tackle rough sleeping, the newspaper said.
She intends to remain in Number 10 for years to come, she said, adding: Theres a long-term job to do.
The former foreign secretary said the UK should build a bridge to Ireland and put the HS2 rail line on hold to focus on a high-speed link in the north of England.
Suggesting he may be able to strike a better deal than Mrs May, he told the newspaper: Unlike the Prime Minister, I fought for this, I believe in it, I think its the right thing for our country and I think that what is happening now is, alas, not what people were promised in 2016.
Setting out an alternative policy platform, the former cabinet minister said: I think we need to make the case for markets.
I dont think we should caper insincerely on socialist territory. You cant beat (Jeremy) Corbyn by becoming Corbyn.
The Prime Minister is expected to set out plans aimed at bolstering her position at the conference this week by announcing measures to crack down on foreign people buying homes.
She added: Its not just about Brexit, its about the domestic agenda as well.
I think were at a very important and historic moment for the UK. There are real opportunities for the UK outside the European Union.
Setting out her plans for a festival in post-Brexit Britain, she said: We want to showcase what makes our country great today.
We want to capture that spirit for a new generation, celebrate our nations diversity and talent, and mark this moment of national renewal with a once-in-a-generation celebration.
Last week the Prime Minister insisted she was not bluffing when she said no deal is better than a bad deal when it comes to leaving the EU.
I believe that we can get a deal, she added. I believe we can get a good deal and thats what we are working for. But nobody should be in any doubt.
The Tory gathering in Birmingham has been marked by a deepening rift over Brexit policy.
The party was also hit by an embarrassing security gaffe as a flaw in the official conference app allowed anyone to log in as a politician, delegate or journalist attending the Birmingham event simply using their email address.
The personal details in the app included personal mobile numbers for every cabinet minister, MP, and journalist attending.
Tory chairman Brandon Lewis apologised for the breach of security and the UKs data watchdog said it would make enquiries about the case.
Activists and journalists heading to the conference discovered the major security problem in the official app which many use to keep track of events.
Mr Lewis said the technical issue had been resolved but we are investigating the issue further and apologise for any concern caused.
The Information Commissioners Office said it would be making enquiries with the Conservative Party and organisations have a legal duty to keep personal data safe and secure.