It is insane for the Republicans to dismiss impeachment before a proper investigation has even been performed. What prosecutor would say he is not going to prosecute a suspect in a serious crime before a police investigation is done? If a prosecutor did that, he should be fired, and so should these useless congressmen.
Yet, this is exactly what the Republicans are doing. They should be pushing for an impartial special prosecutor to be appointed to investigate Obama, instead of making excuses why he cannot be impeached, removed and punished. After the investigation is over, then you decide, if it is worth pursuing or not. Even, if they decide not to impeach, it would be extremely useful to have an official report from a formal investigation of Obama’s wrongdoing.
The Republicans do not fear that nothing will turn up. They are afraid that crimes and abuse of office would be formally exposed and officially documented. Then, they would have to do something about it, even if their knees are knocking loudly.