In this age of leader-centric politics, John Baird’s surprise resignation as Foreign Affairs minister offered a reminder of prime ministerial power and the declining influence of cabinet government.

The two most important cabinet posts in any government are Finance and Foreign Affairs. They are the policy and political anchors for what matters above all: domestic prosperity and international influence. Everything else revolves around how well these two marquee ministers perform their roles.

It’s no overstatement to say that prime ministers are most engaged when it comes to budget-making and foreign affairs. The budget remains the critical political event of the year, demanding significant face-time from the PM to arbitrate competing spending and cutting options. The proliferation of international summits from G7 to G20 means the prime minister is called upon to travel extensively representing Canada. (I’m reminded of an old Woody Allen quip — “Seventy percent of success is just showing up.”)

No surprise, then, that the income-splitting and child tax benefit announcements of last fall were squeezed between two foreign trips by the prime minister.

Now, in less than a year, Prime Minister Stephen Harper has lost both of his lieutenants in these key positions — first Jim Flaherty, now John Baird. Beyond their longevity in these positions, Baird and Flaherty were the most influential voices in Mr. Harper’s cabinet — which perhaps explained their longevity in the first place.

Filling such gaps often presents more risk than reward for a prime minister, particularly one at such a late stage in his mandate.

In seeking replacements, three factors will matter most.

The first is location. Mr. Flaherty and Mr. Baird represented the Ontario leg of the Alberta/Ontario Conservative political axis that dominates this government’s orientation. With a PM from Alberta, the key economic portfolio and the foreign affairs job needed to live in seat-rich Ontario. Finance Minister Joe Oliver hails from Ontario — but he lacks Mr. Flaherty’s political weight.

Mr. Harper’s new Foreign Affairs minister can expect little latitude in the conduct of foreign policy. The prime minister’s senior status on the international stage and personal knowledge of most leaders and issues will make the next foreign minister more of an adjunct and courtier of the PM and his office.

The second factor: political and communications skills. Finance and Foreign Affairs are the only portfolios where misspeaking carries real consequences. Financial markets can shift and international relations can chill over words spoken in haste. Navigating clamouring domestic and foreign constituencies demanding money and attention is no easy task. Mr. Flaherty and Mr. Baird did so with skill.

The third factor is loyalty. In any other portfolio, a minister can speak out of sync with his prime minister without causing profound problems. That’s not the case in Foreign Affairs and Finance. These two ministries present the government’s ‘face’ on its economic and foreign policies; any discord, dissent, or just plain daylight between portfolio and PM can undermine the government’s political integrity and stability.

Recall the kind of discomfort the government endured when differences emerged publicly between Mr. Flaherty and Mr. Harper on the virtues of income-splitting. And who can forget the toxic atmosphere between Prime Minister Jean Chretien and Finance Minister Paul Martin?

Mr. Harper’s selection of Mr. Oliver in Finance reinforces each of these factors. He’s from Ontario, he’s skilled enough in politics and communications to avoid mistakes, and he’s obviously loyal to the prime minister.

More revealing, though, is what this situation tells us about the prime minister and his political situation today. Despite almost a decade in power, he remains more asset than obstacle politically within the party and government. This gives him the whip-hand in driving the government’s domestic, economic and international relations agendas. He has not been cautious about doing so.

So Mr. Harper’s new Foreign Affairs minister can expect little latitude in the conduct of foreign policy. Beyond the policy constraints of the government’s ‘principled’ approach to what’s good, bad, and ugly in the world, the prime minister’s senior status on the international stage and personal knowledge of most leaders and issues will make the next foreign minister more of an adjunct and courtier of the PM and his office.

The rise of ‘prime ministerial government’, with its attendant centralization, is a genuine concern for observers of Parliament. When ministers matter less than the PMO, and when any public service counterweight has long since atrophied, all that is left is for the “centre” to hold fast so that, as Yeats wrote, things do not “fall apart”.

The appointment of the next Foreign Affairs minister will prove this once again.

David McLaughlin was chief of staff to Prime Minister Brian Mulroney, New Brunswick Premier Bernard Lord and Finance Minister Jim Flaherty. He served as deputy minister of Policy and Planning and Intergovernmental Affairs in the New Brunswick government.

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