The prime minister's inner circle is ramping up another lobbying push in Washington to terminate American tariffs on steel and aluminum.

Two senior government sources say that ministers with connections to American national security portfolios will be tasked with reaching out to specific U.S. officials to push Canada's anti-tariff message.

The campaign is based on Canada's long-standing position that the tariffs are both illegal and absurd.

Last June, the Trump administration invoked a rarely used national security provision — Section 232 of the Trade Expansion Act of 1962 — to impose 25 per cent tariffs on imported steel and 10 per cent tariffs on imported aluminum.

The tariffs are based on the argument that, in the event of a national emergency, the U.S. needs robust domestic steel and aluminum industries. Canada has openly attacked the tariffs, pointing out that Canada is not a threat to U.S. national security.

One source said the new lobbying campaign actually began when Foreign Affairs Minister Chrystia Freeland met with U.S. Secretary of State Mike Pompeo during a visit to Washington in December.

Early in the new year, Defence Minister Harjit Sajjan delivered a similar anti-tariff message over the phone to the new U.S. acting Secretary of Defense Patrick Shanahan​.

And Finance Minister Bill Morneau also made Canada's case during a face-to-face meeting with U.S. Treasury Secretary Steve Mnuchin in Washington yesterday.

Now, the lobbying push is seeking new targets. Officials at the Canadian embassy in Washington are drafting a list of influential Americans who may be open to Canada's message.

Once that list is complete, individual ministers will be tasked with reaching out to those officials, by phone or in person, to press Canada's case.

Both Freeland and Morneau will use the upcoming World Economic Forum in Davos, Switzerland as a forum to meet with their American counterparts and push them to nix the tariffs.

They won't see U.S. President Donald Trump there. Trump announced on Twitter today that he would be skipping the forum to focus on the current federal government shutdown and a swelling dispute with House Democrats over his demand for a border wall.

Because of the Democrats intransigence on Border Security and the great importance of Safety for our Nation, I am respectfully cancelling my very important trip to Davos, Switzerland for the World Economic Forum. My warmest regards and apologies to the <a href="https://twitter.com/wef?ref_src=twsrc%5Etfw">@WEF</a>! —@realDonaldTrump

Paul Moen, a principal at Earnscliffe Strategy Group and an international trade lawyer, said Canada's strategy makes sense — but it should also reach out to business and labour leaders and the new faces in Congress who took office in the November midterm elections.

"With the new Congress in place, that's a new opportunity to build some new relationships, build on some old ones, but also to broaden the engagement with the business community, with the labour community," he told CBC News.

But Mark Rowlinson, a spokesman for United Steelworkers Canada, said the window for charm offensives has long since closed and it's time for Canada to draw "a line in the sand" by refusing to ratify the revamped North American trade deal until the tariffs are dropped.

"I'm skeptical​," he said. "It's clearly the case that Canada has never posed a threat to U.S. national security, and I don't think anyone on either side of the border has ever really taken that seriously. Canada has engaged in a number of charm offensives ... and so far, those efforts have yielded next to nothing.

"What they should be doing is saying, 'We will not sign, we will not ratify the new Canada-U.S.-Mexico trade agreement, unless and until these tariffs are dropped."

In fact, neither of the two senior government sources who spoke to CBC News is optimistic that Trump will abandon his enthusiasm for tariffs any time soon.

On Tuesday, Trump tweeted a defence of his tariff policy by quoting an interview on Fox News with Mark Glyptis, a local president of the United Steelworkers union from West Virginia.

“The President is the biggest and best supporter of the Steel Industry in many years. We are now doing really well. The Tariffs let us compete. Was unfair that the Steel Industry lost its jobs to unfair trade laws. Very positive outcome.” Mark Glyptis, United Steelworkers —@realDonaldTrump

One of the sources said that Canada will be stepping away from any arguments that connect the tariffs to the updated North American free trade agreement.

Some American lawmakers and business leaders who oppose the tariffs have said publicly they should be dropped, since they were meant only to serve as leverage in the trade negotiations.

One of the sources told CBC that Canada doesn't want to touch that argument because it's too similar to the line Mexican officials are taking in their own push to end the American tariffs.

Canada does not want to be lumped in with Mexico, the source said, because Mexico might end up agreeing with American demands for export quotas on steel.

CBC News has reported that American trade officials want both Canada and Mexico to accept caps on how much steel they can import into the United States, based on a portion of what was imported in 2017.

"That's crazy," said the source, adding Canada will not entertain the idea of accepting quotas.