The steady stream of migrants across European borders has sparked debate on the federal campaign trail over what role Canada should play in addressing the humanitarian crisis.

NDP Leader Tom Mulcair and Liberal Leader Justin Trudeau accused the Conservative government Wednesday of failing to live up to its promise to resettle thousands of refugees from Syria and Iraq.

“Mr. Harper has failed,” Mulcair told reporters in Kamloops, B.C. “Conservatives can’t be trusted on this.”

“This is the worst refugee crisis since the Second World War. The images are horrific.”

Mulcair said the NDP takes the situation “extraordinarily seriously” and will “do our part” to help refugees, but he did not outline specific solutions.

Trudeau, meanwhile, told a news conference in Trois Rivieres, Que., that the Conservative government “hasn’t once lived up to even its meagre commitments” to accept refugees from Syria and elsewhere.

At a later rally in Quebec City, Trudeau told reporters he had implored Stephen Harper months ago to not only live up to his promise to admit 10,000 Syrian refugees, but to increase the commitment to 25,000.

At a campaign stop in North Bay, Ont., Wednesday, Harper said a refugee policy alone cannot solve the problem of Islamic State militants who are driving people from their homes in Syria and Iraq.

“We have resettled already some 20,000 Iraqi refugees and a couple thousand Syrian refugees and we have plans to do more,” he said.

“But I would say repeatedly that, as we are doing more, we cannot lose sight of the fact that refugee resettlement alone cannot solve this problem, as long as we have organizations like ISIS… creating literally millions of refugees.”

To stem the refugee tide, Canada needs to take “a firm military stance on ISIS,” he said. “And that’s what we’re doing.”

Harper added that Canada is “the largest per capita receiver of immigrants and new arrivals in the entire world,” as well as one of the biggest contributors of aid in the Middle East.

He also said Canada needs to provide support for European countries dealing with border control issues as refugees come through. He did not say how that could be done.

Last January, the Conservatives promised to bring in 10,000 Syrian refugees over three years. But for months, they refused to release information on how many Syrians were actually arriving in the country.

The Citizenship and Immigration Department finally released some data last month saying that 1,002 Syrians had resettled to Canada as of late July 2015. The department has also said that Ottawa had fulfilled a 2013 promise to resettle 1,300 Syrian refugees by the end of 2014.

Last month, Harper said a re-elected Conservative government would bring in 10,000 more refugees from the Middle East over the next four years.

Many of those who have arrived in recent years have been sponsored by religious groups, who raise money to support the government-approved migrants after they arrive.

Rick Cober Bauman, of the Mennonite Central Committee Ontario, said his group is already preparing the paperwork to sponsor several thousand possible refugees.

It is estimated that more than 332,000 migrants have entered Europe so far this year. Many of them are men, women and children fleeing the war in Syria, while others have fled Iraq and Afghanistan.

The crisis has intensified in recent days, with countries such as Hungary trying to prevent the refugees from seeking asylum in Germany and elsewhere in the European Union by shutting down train services.

With files from The Canadian Press and a report from CTV Ottawa Bureau Chief Robert Fife