At stake is the system's capacity to become an aggressive president, which will inevitably be seen by his fervent base as an attempt by elites to subvert a democratic election.
Mueller is inexorably marching towards the end of his life investigation and democrats flex muscle.
Such a move would be unleashed a fresh constitutional argument and is likely to infuriate the president if the courts,
Trump signaled "ready to move ahead of the failure of the latest talk with congressional Democrats on solving the government shutdown."
"If this I do not work out, I probably almost say, "Trump said. Michael Cohen, the former personal attorney who flipped on trumps, would testify in public next.
Balance of power
Tension among the three branches of government is a built-in feature of the US system, and presidents from John Adams to Barack Obama have chafed at constraints on their power
It is difficult to point to any time in the modern era when so many of the issues driving the national debate revolve around what a president can legally do and the effectiveness of competing power bases in the federal system.  Some of this can be put down to the character of Trump himself. The President is mercurial and unruly. He's an outsider unfamiliar with the institutional constraints of the US constitutional system. His outlook was shaped in a family business.
Two years in office, Trump has torn at historical standards and stamped over protocol, railing at the Washington establishment.