This is a sham. It doesn't matter if you are a Dem or Rep in this matter. The tax payers footed a 40 million dollar bill for Mueller to perform this investigation. Mueller's testimony could help or hurt Trump. Either way, the people of this country should demand Mueller come in and answer to Congress about his findings and decide for themselves if his report can withstand scrutiny under examination.
The House and Senate need to call him before their committees immediately and Barr should instruct him to answer every question as completely as possible until all questions are answered.