How did Andrew Johnson attack the radical republicans?

Not very well; they did everything in their power to prevent him from exercising the Executive powers of President because they saw him as a Southern sympathizer. Congress voted to reduce the number of seats on the Supreme Court during Johnson's presidency to prevent him from nominating a justice; they also impeached Johnson and attempted to remove him from office for reasons as diverse as violating the 1867 Tenure of Office Act to libeling Congress.