WASHINGTON—Republican presidential candidate Ben Carson is calling for the U.S. to deploy soldiers to parts of the Canadian border.

Carson, who is fading quickly in the polls, made the proposal as part of the “Seven Steps to a Safer America” anti-terrorism plan he issued on Tuesday.

The sixth step: “President Barack Obama and Congress should immediately deploy the National Guard and military troops to patrol the U.S. southern border as well as designated spots along the northern border.”

He did not identify the spots or say why he believes current security measures along the Canadian border are inadequate.

Carson is the second Republican candidate to suggest new defensive measures up north. Wisconsin Gov. Scott Walker, now out of the race, was widely ridiculed for musing about the possibility of a wall along the Canadian border.

Canadian diplomats spent years after the 9/11 attacks of 2001 attempting to combat the widespread myth that some of the hijackers crossed into the U.S. from Canada.

Carson has been plagued by a perception that he is unschooled on foreign policy. He has lost nearly half of his national support in the month since the Islamic State terrorist attack on Paris, and he now sits in fourth place behind businessman Donald Trump, Texas Sen. Ted Cruz and Florida Sen. Marco Rubio.

His security plan includes a formal declaration of war against the Islamic State, the formation of a stronger coalition to fight the extremist group, and the creation of a “refugee safe zone” in northeast Syria. Carson does not want the U.S. to accept refugees.