The problem with the grand jury for Trump is this: Clinton was called before a grand jury, and he lied, and got impeached for it. If Trump, who apparently cannot avoid lying, is called before a grand jury, he will inevitably perjure himself. And with the way his approval ratings are dropping, and with the fact that the Republicans would all prefer Mike Pence, Trump will get impeached and convicted.

So, whether or not Trump colluded with Russia, if he's called to testify before a grand jury, it's the end of his presidency. Because he will inevitably tell a lie, and lying to a grand jury is a crime.

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