After John Baird bid farewell in the House of Commons, the prime minister was quickly on his feet to embrace the man who had served him so well in cabinet since 2006.

It was a very public recognition of what is a substantial loss to both Stephen Harper and his government.

For all of Baird's pugnacious partisanship, and sometimes because of it, he will be difficult to replace.

No matter the portfolio, Baird embraced the government message and sold it widely.

It was something the prime minister also highlighted in his statement: "John has always been willing to do a lot of heavy lifting in my various cabinets and has assumed daunting new responsibilities with unsurpassed energy, commitment and professionalism, never losing sight of the fact that he was serving the Canadian people."

But Baird was also serving Harper, and doing it better than many.

And with his departure, Harper has lost one of his strongest and most reliable communicators.

As minister of the environment, Baird slammed the Kyoto protocol as a "risky, reckless scheme." It became a kind of Conservative slogan for everything the government believed to be wrong with the international agreement, while also conveniently characterizing his opponents who supported it.

As foreign affairs minister, Baird condemned the Russian invasion of Crimea as being "akin to war." He flew to Ukraine to walk with protesters in Maidan Square just weeks after the Yanukovich government was toppled and some demonstrators were killed.

That kind of blunt, in your face, political messaging and action is not something every minister is able or willing to deliver.

But while Baird pushed the message, he was also an assertive and strong presence at the cabinet table.

Willing to challenge the boss

Baird calls Harper "his friend and mentor," but that doesn't mean he bowed to the prime minister.

Those who know him agree Baird brought a strong point of view to the cabinet discussions and was able to argue effectively and directly to the boss, even if it wasn't always welcome. One insider said he was "forceful" in his arguments, but was always able to temper them with his sense of humour as he tried to make it palatable for everyone else.

The challenge for Harper is that those voices of willing dissent are increasingly diminished around the cabinet table. Those notes of discord are strongly needed, particularly within a majority government, and Harper is said to welcome them as part of his decision-making process.

Former finance minister Jim Flaherty was certainly a loss in that regard. His criticism of the benefits of income splitting led to a heated discussion within the caucus, but at least Flaherty was not fearful of declaring and lobbying for his position.

Baird did some of the same.

One example cited by sources is the way Baird pushed Canada toward a policy of engagement with China. He spoke against other ministers and then chose China for his first bilateral visit as foreign affairs minister, boldly calling it the beginning of a "new era" in relations between the two countries.

Harper has now lost both of those voices.

Conservative strategists point to ministers including James Moore, Jason Kenney and Lisa Raitt as assertive and experienced politicians who will continue to offer advice — but who may now have to step up more.

There is already some concern that socially progressive Conservatives have lost a strong advocate within cabinet. A strategist noted Baird's role in the foreign affairs file allowed him to speak loudly on issues of "conscience."

For instance, Baird condemned the treatment of homosexuals in Nigeria, Uganda and Russia even as a socially conservative women's group slammed him. Baird's office bluntly fired back that he was standing up for principles supported by the "vast majority of Canadians."

Of course, the prime minister can seek out other voices, look to other ministers and, ultimately, he can replace John Baird.

But at least one former Harper adviser says Baird was perhaps most critically a trusted political ally, one whom Harper was able to talk with on just about any topic, a sounding board for strategy and political ideas. It is not something Harper is comfortable doing with just anyone.

When asked who could possibly fill that role in the future, the former adviser came up blank.