According to Mike Allen, Sen. Joe Biden "will release 10 years of tax returns today in an effort to pressure Alaska Gov. Palin to make data available about her acceptance of per-diem travel allowances from the Alaska government when she was at home."
Sen. John McCain has released two years of tax data and Cindy McCain released a two-page form from 2006. Sen. Barack Obama has released returns for each year going back to 2000.