With a clear majority in both houses, Republicans face a difficult choice about whether to compromise with President Barack Obama on a series of issues. Mr Obama has already made it clear that he will not wait for their decision. Instead, he will spend his final two years in office exploring the frontiers of executive power.

Last week bought two expressions of this new posture: the secretly negotiated agreement on emissions Mr Obama announced with Chinese President Xi Jinping, and a statement on net neutrality that advocated regulating internet service providers as “common carriers”.

As soon as this week, the president is expected to move ahead on a third, more politically volatile issue of allowing millions of illegal residents to stay and work legally in the US. The first announcement provoked Republican catcalls. The second made them howl. The third is rendering them apoplectic. At the extreme end, Arizona congressman Matt Salmon said the amnesty plan would be an “impeachable offence”.