Theresa May claimed Labour has "deserted" the "proud and patriotic working class people" as she took her campaign to the north east of England.
She is reaching out to any dissatisfied Labour voters promising to "earn the trust of all our people" if she wins the General Election on June 8.
Following the leak of Labour's election manifesto promising to re-nationalise key industries and end years of austerity, Mrs May will say it is clear that under Mr Corbyn the party had lost touch with its traditional supporters.
In a speech she will say his programme represented a return to "the disastrous socialist policies of the 1970's" and Mr Corbyn's Labour "simply can't add up".
Mrs May said that Labour's manifesto plans could hit ordinary family through tax rises and that the needs of many ordinary people had been abandoned.
"Proud and patriotic working class people in towns and cities across Britain have not deserted the Labour Party - Jeremy Corbyn has deserted them," she said.
"Millions of people here in the north east of England, and across our country, have loyally given the Labour Party their allegiance for generations. I respect that.
"We respect that parents and grandparents taught their children and grandchildren that Labour was a party that shared their values and stood up for their community.
"But across the country today, traditional Labour supporters are increasingly looking at what Jeremy Corbyn believes in and are appalled."
She also highlighted Conservative policies to cap energy bills, protect workplace pensions and improve mental health provision while investing in the armed forces.
"I will be reaching out to those who have been abandoned by jEREM and let down by government for too long. I will be doing everything I can to earn their trust," she said.
"My commitment to them is this: if you put your trust in me, back me, I will strive to be a leader worthy of our great country."
Labour's national campaign chairman Ian Lavery called the move to target the working class "nonsense".
"The wonderful people of the north east of England won't be fooled by this farcical attempt by Theresa May to mask the damage her Tories have done to the lives of working people across the country", he said.