The company said it was expecting strong interest from independent and national retailers wanting to operate a Post Office branch from their premises.
The Post Office has launched a search for retailers to run 70 Crown branches, a day after workers went on strike over the move.
The Post Office said it had already received over 150 expressions of interest from potential retail partners who wanted to benefit from increased footfall into their store and the income they receive from selling and transacting postal products.
Members of the Communication Workers Union (CWU) staged their third strike on Monday in protest at the franchising and closure of Crown offices, the larger branches usually sited on high streets.
The union is opposed to franchising, saying hundreds of jobs will be affected, and is also in dispute over pay for its Crown office members.
Kevin Gilliland, Network and Sales Director at the Post Office said: "We are committed to modernising our Crown network to make it as easy as possible for customers to access our services and bring in new business.
"It is currently losing £40 million a year of public money. Partnering 70 branches with retailers and investing £70 million in 300 Crown branches is the best way to keep our branches on high streets and in city centres across the UK.
"These branches serve thousands of customers each week. However, we must change the way they operate to ensure their long term viability. We already have over 10,000 branches which operate through franchises and agreements with retailers so we know this model works.
"We welcome approaches from potential retail partners who want to work with us to provide our customers with high levels of customer service and easy access to Post Office products from a modern retail space."
The Post Office said that subject to a public consultation, the Crown branches will be transferred to retail operators before April 2015. Petitions against franchising have been launched in areas affected by the plans.