Can Congress constrain Trump in September ?

Some Republican senators have begun to shed their reluctance to criticize the presidency of Donald Trump. When Congress returns from its August recess, they’ll have the chance to do something about it.
Only Congress and the courts have the constitutional power to constrain an executive. The courts have been performing their assigned role, placing constitutional barriers in the way of demagogic campaign promises becoming law.
Congress, under the leadership of Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan, has not been completely AWOL. Sanctions on Russia, for example, imposed over the objections of a president who routinely validates the criminal regime of Vladimir Putin, showed how Congress can properly fulfill its obligations.
But the Trump presidency requires Congress to exercise a much higher degree of oversight.
This is a political challenge for Republican leaders. It is not, however, a constitutional challenge. The investigative and oversight capacities of Congress are immense. (Anyone who doubts this should review the history of serial Benghazi investigations that preceded Hillary Clinton’s presidential campaign.)
McConnell and Ryan have broad powers to influence a rogue executive, both publicly and privately. To take just one example, the issue of presidential emoluments is of great interest to good-government types and a sensitive issue for the White House. Trump’s practice of profiting from public office through his Washington hotel and other commercial properties raises profound ethical and constitutional questions.
This is an ideal opportunity for Congress to air the issues and investigate the facts. It has not done so. If McConnell and Ryan are uninterested in ethics, they could at least use the interest of others as leverage over the White House.
Congressional leaders eager to improve the functioning of the executive branch, and the divisive conduct of its chief, could put hearings about the emoluments clause of the Constitution, and Trump’s apparent violations of it, on the public agenda.
Whether such hearings are ever held would depend on Trump’s response. Even if Trump forced Congress to make good on its threat, the speed and scope of any investigation would be entirely up to the Republican leadership; they could be calibrated to presidential behavior.
“The president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful,” Senator Bob Corker said last week, referring to Trump’s horrifying reaction to a neo-Nazi demonstration in Charlottesville, Virginia.
McConnell and Ryan have ample political power, guaranteed by the Constitution, to constrain an increasingly erratic and possibly dangerous president. What they have lacked, thus far, is sufficient courage to use it.

—Bloomberg