Why in the world would Trent Lott resign? Was it due to what the liberal media and Bush did to him?

I know this African American man that was real disabled and cannot drive and during the Clintons great "I feel your pain" years he could not help him and Sen. Lott did get him help after they jerked him around, he was from Laurel, so why has lott got to resign, i mean Mississippi hasn't got much, just ranked over Louisiana, New Hampshire and New Mexico, Mississippi needs him.