The protests, he claimed, presented a threat to residents’ safety. There have also been racial attacks reported.
Vehicles and tents have blocked roadways in Ottawa’s downtown area, paralyzing the city.
The “Freedom Convoy” was inspired by a new law requiring all truckers to get vaccinated before crossing the US-Canada border last month, but the protests have evolved into larger objections to Covid health rules.
The demonstrators have since assembled outside Parliament Hill in downtown Ottawa, and their demands have expanded to include eliminating all such mandates across the country and rejecting Prime Minister Justin Trudeau’s government.
Watson, speaking on Canadian radio station CFRA, said the protesters were behaving increasingly “insensitively” by continuously “blaring horns and sirens, [setting off] fireworks and turning it into a party”.
“Clearly, we are outnumbered and we are losing this battle,” he said, adding: “This has to be reversed – we have to get our city back.”
The mayor did not give details about what measures he might impose, but police said on Sunday that they would step up enforcement, including possible arrests of those seeking to aid the protesters by bringing them supplies like fuel, toilet paper and food.
A state of emergency will give the city additional powers, including access to equipment required by frontline workers and emergency services.
Many Ottawa residents have objected to the demonstrations.
Complaints range from idling trucks that impede traffic and makeshift wooden structures in city parks to lost income and fears of harassment and even violence.
Police have said they are concerned about how the convoy has attracted far-right and extremist elements, and on Sunday confirmed they were dealing with more than 60 criminal investigations, with alleged offences including “mischief, thefts, hate crimes and property damage”.
“There have been racist signs, there have been a lot of reports of people being assaulted and harassed if they wear a mask,” Stephanie Carvon, Ottawa resident and former national security analyst for the Canadian government told the BBC.
She added that some organisers of the protest hold extremist views but have “successfully framed their actions in the name of the pandemic and ending the mandates, so they’ve earned the sympathy of a lot of Canadians who may not necessarily realise where this has come from”.