1. There is no need to even mention the word "impeachment" when you're dealing with a fabricated scandal like this.
2. There's no need for any Republican to do this when you already have people like Diane Feinstein, former FBI Director James Comey, and interim FBI Director Andrew McCabe on the record saying exactly what you've said here.
You missed the point. The GOP has ammunition and to spare, if they cared to support Trump. But they have no interest in supporting him. They enjoy seeing him viciously, unfairly and relentlessly attacked far more.