QUEBEC CITY -- Interim Conservative leader Rona Ambrose is sharpening her attack on Prime Minister Justin Trudeau as the parties prepare to head back to Parliament next week.

Monday will be the first day back in the House since Dec. 15, and both the NDP and Conservatives are holding caucus meetings this week ahead of the return. The Liberal cabinet met in Calgary earlier this week.

In her speech to caucus, Ambrose described the Conservatives as a party that works for Canadians and said it's the only party that fights for taxpayers. In contrast, she said the Liberals are raising taxes and don't have a plan to deal with the challenges of a potential renegotiation of NAFTA under U.S. President Donald Trump.

Ambrose also raised a number of controversies the Liberals have encountered since taking office in the fall of 2015, including a recent ethics probe over Trudeau's holiday on a private island owned by the Aga Khan.

"Justin Trudeau thinks that these ethics rules don't apply to him. He thinks the rules are for others -- not wealthy, well-connected people like him," Ambrose said.

"Working Canadians can't take much more. It's time for Justin Trudeau to change his priorities. The fun is over," she said.

Ambrose called on Trudeau to share his plan to protect free trade with the U.S. and Mexico, and painted his first year in office as one of travel and selfies.

"It's time for the prime minister to show some leadership on the economy.... Frankly, [Trudeau] is never around. He skipped question period 58 per cent of the time, favouring photo ops over responding to his job and questions about his government."

Trudeau is currently in Saskatchewan as part of a series of town halls being described as a listening tour.

Canada-U.S. relations a challenge for opposition

The caucus spent Thursday morning listening to the authors of a book on Quebec's evolving identity, Le coeur des Quebecois. The book examines how Quebeckers once defined themselves mostly in terms of whether they'd vote yes or no on secession and how that's changed since the mid-1970s.

The afternoon sessions include reports by parliamentary critics and a communications report to set the messaging for the upcoming sitting of Parliament, while Friday will be spent on economic issues.

There's no time set aside specifically to discuss Canada-U.S. relations, but the topic is certainly expected to come up during the other sessions. Ambrose and Randy Hoback, the party's critic for Canada-U.S. issues, spent several days in Washington, D.C. last week to meet with U.S. politicians.

One challenge the party will face is how to criticize the Liberal government during a delicate time in Canada-U.S. relations.

Tony Clement, the party's public safety critic, says they have to respect Trump's "America first" policy, on which he campaigned for president.

"But at the same time we're here for Canada," Clement said. "And to me this doesn't have to be a partisan issue. We should be here for Canada, but if Mr. Trudeau fails to protect Canadian interests then we'll have something to say about that."

"When you're in Washington, you have to be a Canadian first. When we're here in Canada, we have to have a good Canadian debate about Canadian interests, present day and the future. I think there's nothing wrong with that, that's how democracy works. It doesn't work if we're all agreeing 100 per cent of the time," Clement said.

The caucus meetings will wrap up with a press conference Friday afternoon.