Nixon was caught by hard evidence (the tapes) that he was involved in a crime. So far such evidence has not surfaced in O's case.
There clearly is a cover up going on related to the IRS targeting. The GOP should state as such, and without a lot of drama, list off the scandals. And state, "support us so we can get to the bottom of these matters". Assuming they win the Senate, then have Lerner (and any other stooges) arrested & offer immunity. Then see what shakes out. In the process, quietly remind the press that the Dems wiretapped & harrassed reporters and sources (like Nixon).
Patience friends, patience. And we can leave the left badly damaged for a generation.
