Barron’s spoke with Tobin Marcus, head of U.S. policy and politics with Wolfe Research and a former White House advisor during the Obama era, about what could unfold if Trump follows through on such a move. An edited version of our conversation is below.

For a moment on Wednesday, it looked like President Donald Trump would finally attempt the improbable and fire Federal Reserve Chair Jerome Powell.

As frequently happens with government building projects, the project has blown past its planned budget, with the cost skyrocketing from an initially large $1.9 billion to an eye-popping $2.5 billion....