The National Health Action Party (NHA) was formed last month by a group of health professionals to stop the commercialisation of the NHS.
Its founders believe the reforms could have been abandoned if the BMA and royal colleges had spoken out against them earlier and more strongly.
The NHA, which is aiming to be an influential minority party, will field 50 candidates in general election constituencies and contest some council seats. It plans to reject any offers to run as part of a coalition.
The founding members include three BMA council members - south London GP Dr Louise Irvine, consultant radiologist Dr Jacky Davis and consultant oncologist Dr Clive Peedell.
Dr Peedell said: 'It is only with hindsight that people now realise that if the BMA, along with the royal colleges, had come out against the Bill earlier, it could have been stopped.
'The BMA was one of the few organisations that did come out against the Bill but the royal colleges were far too slow, apart from the RCGP.'
The party now aims to do all it can to reverse the reforms.
The NHA wants to go further than Labour, calling for the abolition of the 211 clinical commissioning groups (CCGs) being set up to take over from PCTs. Labour plans simply to ask CCGs to work differently.
Dr Peedell denied that doctors' involvement in the NHA would undermine the BMA. 'To achieve change, you need multiple platforms - negotiations with unions, campaigning and politics.'
A BMA spokesman said: 'The founders of the NHA party have displayed huge energy and commitment. The BMA itself, however, is strictly non-partisan.
'We were one of the earliest and most vocal critics of the current reforms to the NHS in England, as well as those by the previous government.'
Dr Irvine said the action that doctors had taken to date to oppose the reforms - standing for election to the BMA council, sending letters to newspapers and taking part in protests - had made no difference. 'We want to take the fight into the political realm,' she said.
Dr George Rae, chief executive officer of Newcastle and North Tyneside LMC, said: 'The NHS will be a big issue at the next general election and if the party is targeting marginal seats in areas where there are question marks over services, it could be successful.'
Dr Helena McKeown, BMA council member and Wiltshire GP
I think it will be hugely successful in drawing attention to the consequences of the Act, as they are using high-profile tactics, such as targeting Cameron's seat.
Dr Ron Singer, Medical Practitioners' Union president
We welcome the publicity generated for the NHS. Many doctors are disappointed with the BMA's response to the Bill. It was late, it wasn't robust and it focused on trying to amend it.
Dr Peter Swinyard, Family Doctor Association chairman and Swindon GP
It needs to be a constructive debate. Saying: 'Repeal, repeal, repeal' is not going to get better patient care, as it would cause a massive vacuum unless you had plan B really worked out.