Prime Minister Justin Trudeau will shuffle his cabinet next Wednesday as his government readies for the next election amid shifting federal-provincial relations, CBC News has learned.

The Canadian Press reported earlier this week that a shuffle was coming within the next week. A source who spoke to CBC News on condition of anonymity confirmed the changes would be announced Wednesday.

It's not unusual for governments to shake things up late in a mandate and replace ministers who are not expecting to seek re-election. However, that does not appear to be the main motivation for next week's shuffle, since most if not all current ministers are indicating they want to run again in 2019.

Rather, the source said, next week's changes are in part a recognition of shifting circumstances over the past year, especially in the area of federal-provincial relations.

Those changes include Progressive Conservative Doug Ford's defeat of Trudeau ally Kathleen Wynne in Ontario's provincial election last month and challenges on several fronts to the framework agreement on climate change reached between Trudeau and the provinces nearly two years ago.

Cabinet shuffles are also an opportunity for a prime minister to move or replace poor performers with new blood, or to bring a new tone to some ministries. The source did not offer details on who might be moved next week.

Trudeau does have to fill the vacancy created by the permanent expulsion of MP Kent Hehr from his cabinet. Hehr was allowed to stay in caucus but was removed from his post as minister of sport and persons with disabilities after he was investigated over allegations of sexual harassment.

Since then, Kirsty Duncan has been shouldering double duty with Hehr's old portfolio and her own job as science minister. Trudeau also could opt to expand his cabinet by splitting the duties of Bardish Chagger, who is government House leader as well as minister for small business and tourism.

But it seems unlikely that Trudeau will move some of his top ministers from their front bench posts — especially ministers who play key roles in Canada-U.S. relations.

In January 2017, Trudeau shuffled his cabinet and reoriented the focus of his government to respond to the election of U.S. President Donald Trump. With NAFTA negotiations unresolved and Trump ramping up a continental and trans-Atlantic trade war with G7 and NATO allies, there may be a handful of portfolios that Trudeau simply can't change.