A 45p rate, which currently kicks in for incomes exceeding £150,000, would apply to earnings above £62,000, the group suggested in plans disclosed to The Telegraph.
More than two million middle-class workers would get a tax cut of up to £2,000 a year under the proposals, according to estimates.
The Budget is set to take place on 19 March.
The number of people who currently pay higher rate tax stands at some 4.4 million.
The Conservatives have said they are assessing ways to reduce the number of people paying the 40p rate.
David Skelton, a Tory candidate who leads Renewal, said: “More and more people on middle incomes have been dragged into paying the 40 per cent rate of tax over the past decade or so. That includes teachers, nurses, bricklayers, police officers and Tube drivers.
“These are not the type of people who should be paying higher-rate tax.”
