Mueller is really starting to worry Trump:
Some of President Trump’s lawyers are exploring ways to limit or undercut special counsel Robert S. Mueller III’s Russia investigation, building a case against what they allege are his conflicts of interest and discussing the president’s authority to grant pardons, according to people familiar with the effort.
Trump has asked his advisers about his power to pardon aides, family members and even himself in connection with the probe, according to one of those people. A second person said Trump’s lawyers have been discussing the president’s pardoning powers among themselves.
Trump’s legal team declined to comment on the issue. But one adviser said the president has simply expressed a curiosity in understanding the reach of his pardoning authority, as well as the limits of Mueller’s investigation.