Some in the White House attribute the new push to arguments that have hit the mainstream — and Trump’s radar — thanks to Michael Anton, a former spokesman for the National Security Council, who serves as something of a bridge between Trump world and the world of Claremont.

Anton made the case for ending birthright citizenship in a July Washington Post op-ed that cited the arguments of Ed Erler, a senior fellow at the Claremont Institute and a constitutional scholar who for years has advocated an end to birthright citizenship. “An executive order could specify to federal agencies that the children of noncitizens are not citizens,” Anton wrote. “Such an order would, of course, immediately be challenged in the courts. But officers in all three branches of government — the president no less than judges — take similar oaths to defend the Constitution. Why shouldn’t the president act to defend the clear meaning of the 14th Amendment?”

Anton has not spoken to the president since he left the White House in April and did not alert the White House to his Post piece in advance. But some White House staffers have contacted him to say that the president welcomes his arguments and encourages him to continue his advocacy. Trump aides have also acknowledged that the piece, and the ensuing controversy around it, helped to elevate the president’s interest in the issue.