Justin Trudeau hit the ground running after an arduous 78-day election campaign and shows no signs of slowing down.

As one of the country's youngest prime ministers ever, Trudeau has already demonstrated he has stamina — but does he have the political capital to enact his long list of electoral promises?

The Liberal government has had to curtail some of its more ambitious commitments early in its mandate and it will surely test the patience of the millions of Canadians who cast their votes for "real change" if or when it backs down from other promises.

Two people who will be hot on his heels are Rona Ambrose and Brad Wall, key entries on our list of political players to watch in 2016. Ambrose, the interim leader of the Conservative Party, has already put Trudeau on notice.

What will she do to hold the government to account? "Just watch me," she said in her maiden speech as interim leader, echoing a catch phrase of the current prime minister's father.

Political observers have always speculated that the popular premier of the Saskatchewan, Brad Wall, had national ambitions. And with the Conservative Party leadership contest set to begin in earnest in the early months of next year, could the premier be one of the first to throw his hat in the ring? First, he'll have to face voters in his own province before making that decision.

CBC News Network's Power & Politics looks at the political players to watch in 2016.

Watch the video montages below, or the full edition of our special episode above.

1. Justin Trudeau

Top 5 Political Players: Justin Trudeau1:14

The prime minister ran on an ambitious agenda of change — and the work that gets done in 2016 could very well define the rest of his four-year mandate. The government has already moved forward with its "middle class" tax cut and a tax hike for the richest Canadians, but much more is left to be done.

The prime minister has promised a dramatic departure from the Harper era — but could the realities of governing clip his wings?

2. Rookie ministers

Top 5 Political Players: Rookie Ministers1:09

One rookie minister — a man with no previous political experience — was tapped to be the face of the government's most important portfolio: Finance.

And Bill Morneau is already facing an uphill battle. The party ran on a platform of "modest" deficits of less than $10 billion a year until climbing out of the fiscal hole in time for the next election. But the Parliamentary Budget Officer, and the department's own numbers, suggest that might be more difficult than originally thought.

But he isn't backing down from the challenge, promising to enact an ambitious multi-billion dollar infrastructure program and restoring cuts to key government departments.

Another minister with little political experience — Jody Wilson-Raybould — has the Justice file, a portfolio that will see a flurry of action in the new year. The government must craft a response to a Supreme Court decision on doctor-assisted death. Medical marijuana and launching an inquiry into missing and murdered indigenous women are two other files that will demand swift action.

3. Brad Wall

Top 5 Political Players: Brad Wall0:53

The premier of Saskatchewan has staked out new ground — he's one of the few conservative voices left on the provincial stage in the face of a tsunami of Liberal and NDP governments nationwide. In fact, Wall is leader of the only non-Liberal or NDP government in the country, after the drubbing the Progressive Conservatives suffered in Newfoundland.

Look for him to be a thorn in the side of the Trudeau government as it pushes its centre-left agenda in 2016.

Wall has already raised red flags about efforts to resettle thousands of Syrian refugees in a short time period. He's positioned himself as a strong defender of the oilsands in the face of national efforts to crack down on climate change. 

In addition to facing an election of his own in Saskatchewan in 2016, some political observers believe he might throw his hat in the ring for the permanent leadership of the Conservative Party. That race will likely get underway in earnest as party stalwarts such as Jason Kenney, Tony Clement, Lisa Raitt and Maxime Bernier consider their options. 

4. Rona Ambrose

Top 5 Political Players: Rona Ambrose0:49

Rona Ambrose took over the leadership of the Conservative Party, on an interim basis, in a caucus vote shortly after the departure of Stephen Harper. The Edmonton-area MP held a number of key portfolios in the Harper government, and she has already proven herself adept at holding the government to account in question period.

In addition to rhyming off carefully-crafted quips in the House, Ambrose has also reoriented the party away from its more right-leaning campaign promises.

She has already backed away from the party's election focus on identity politics, and its aversion for an inquiry into missing and murdered indigenous women. She built her shadow cabinet with a number of the party's most prominent female MPs, including Raitt in the finance portfolio.

The transition from government to opposition is hard for any party. And Ambrose will face a heady Liberal agenda that includes a solution on physician-assisted suicide, legalizing marijuana, tax hikes and an ambitious plan to reform the electoral system.

5. U.S. presidential candidates

Top 5 Political Players: U.S. Presidential Candidates1:14

Pierre Trudeau characterized Canada's relationship with our neighbour to the south in 1969 this way: "Living next to you is in some ways like sleeping with an elephant. No matter how friendly and even-tempered is the beast, if I can call it that, one is affected by every twitch and grunt."

Canadians are watching the Democratic and Republican primaries closely.

Hillary Clinton has already staked out a political ground that some see as hostile to Canada's national interests. She has called Alberta oil some of the "world's dirtiest," and she is an opponent of pipelines.

Despite being an early proponent of the Trans-Pacific Partnership, a key plank in the economic platform of the former Harper government, Clinton says the deal isn't good enough in its current form. As a trading nation, a move towards protectionism could be worrying for Canada.

Donald Trump, the current front runner in the Republican race, holds political positions that would be unpalatable for a great many Canadians.

His embrace of the oil and gas industry likely sits well with business interests in this country. But he, too, has advocated some protectionism and a form of economic nationalism that could pose problems for exporting industries.