At legal border crossings either country can turn back or accept people trying to enter either country. Canada and the US have a treaty that says that persons trying to cross the border at legal crossing points must be accepted by the sending country if they are sent back. Additionally, "refugees" who have landed in one country are not allowed into the other country as refugees.
People crossing the Canadian border illegally into Canada CAN claim to be refugees. They will get a hearing and, in most cases, will be sent back or to their country of origin.
I'm not sure exactly who we're talking about here.I'm assuming that the people that 48% of Canadians want expelled are Mexicans who,fearing deportation from the US,are taking your young,charismatic PM at his word that "our doors are open".I'm also assuming that the foreigners we're talking about entered Canada in ways that violate your laws (that is,sneaking over the border).
It's pretty common knowledge that our common border is a pretty porous one.No troops....not many police (I,personally,have been to a spot in Vermont where I could easily sneak into Canadian territory without the permission of one of your border officials )...and lots (and lots!) of wide open country.
OTOH,if we're talking about moslems that might be a different matter.
Canada passed a law in 2004 that effectively bans anyone entering Canada via the United States from claiming refugee status at the border, called the Safe Third Country Agreement.
“The presumption is that the United States is a safe country so they don’t need to request protection in Canada if they can already request asylum, protection or refugee status in the United States,
Last month as thousands shared photos of smiling Canadian
police helping a family of Somali refugees fleeing U.S. border agents, a Reuters report confirms a much different reality.
Moments after that family managed to cross into Canada, they were all handcuffed and placed in Canada’s migrant detention system.