At the pivotal moment a freshly crowned Thomas Mulcair needed to ignite his party faithful and wow the Canadian masses, the NDP's great hope for power delivered a convoluted victory speech with all the passion of phoning for a cab.

As Mulcair's second oratorical flop in as many days sucked the energy from the Toronto convention hall Saturday night, it is a safe bet the loudest applause for the speech was from federal Liberals across the land. Mulcair and his promise to lead the NDP toward the political centre clearly threaten no one more than the Liberal Party.

Looking confident and relaxed, Mulcair emerged from his weekend victory promising to go into bloody battle with Prime Minister Stephen Harper and the Conservatives, barely mentioning the third-party Grits.

In return, the Conservatives welcomed Mulcair's victory with an online attack, calling him "an opportunist whose high-tax agenda, blind ambition and divisive personality would put Canadian families and their jobs at risk."

But beyond all the partisan rhetoric, Harper and Mulcair are more allies than enemies in their pursuit of one key political goal — the decimation of the federal Liberal party.

Worst outcome for Liberals

Just as the Conservatives could not have won their majority without attracting right-leaning Liberal voters, so Mulcair knows the NDP's electoral fortunes depend in large measure on Liberals on the left.

Newly-elected NDP Leader Thomas Mulcair is greeted by the NDP caucus in Toronto on Sunday. (Chris Young/Canadian Press)

Among all the leadership contenders, Mulcair was by far the Liberals' worst-case scenario.

First and perhaps foremost, the popular Quebecer has the best chance among all the leadership hopefuls of being able to sustain the NDP's popularity in a province that is home to 58 of its 102 seats nationally.

Second, Mulcair is a seasoned parliamentarian with the ability to be a formidable performer in the daily Commons fracas that feeds so much of the national media’s political coverage.

Third, he can raise money, his campaign having amassed by far the largest war chest of any of the NDP leadership candidates.

The ability to build a slick party fundraising machine and attract millions of dollars in relatively small contributions has become critical since the Conservatives moved to phase out per-vote public subsidies that have been the bread and butter for all parties for more than a decade.

Fourth, as a former provincial Liberal, Mulcair can credibly lead the NDP toward the centre without having to reinvent his political ideology, and all the doubt that could raise in voters' minds. Witness interim Liberal Leader Bob Rae, who can't shake his record as NDP premier of Ontario years ago.

Finally, Mulcair and his party have a window of opportunity to kick the Liberals while they are leaderless, cash-strapped and demoralized.

In sum, the New Democrats have chosen a leader who at least appears to have the essentials to turn his party's so-called "orange crush" in the last election into a new norm in Canadian politics.

That doesn't mean it's time to write off the Liberals.

NDP faces divisions

Despite much hugging for the cameras, the NDP is emerging from its marathon leadership race as a party deeply divided.

Mulcair was the first- and even second-ballot choice of barely a third of the party members who voted.

Among the other two-thirds, antipathy towards him was never far below the surface of the convention — even to the point of a rare public bashing by a former party leader, iconic NDPer Ed Broadbent, on CBC’s Power and Politics with Evan Solomon.

Mulcair's move toward the centre, jettisoning the NDP's traditional socialist roots along the way, is a virtual guarantee large numbers of the rank and file won't follow without a fight for their long-held causes.

Already, this is a party lacking enthusiasm in the wake of Jack Layton's death.

Only half of all party members eligible to vote for the leadership bothered to cast ballots, and even the crowd that paid big money to attend the Toronto convention spent much of the time sitting on their hands.

The long delays in voting that plagued the convention may not have been the party's fault, but reflected poorly on NDP competence nonetheless.

Then there's Mulcair, known for being prickly, stubborn and not inclined to welcome dissenting opinion and uncomfortable advice. Sources say his underwhelming victory speech was his own — he apparently tossed a professionally written text and refused a teleprompter.

Mulcair didn't even make it past his first lunch as the NDP's new leader before some of the party's brightest and most experienced staffers were running for the exits.

And in Quebec, there are doubts about how many of the NDP’s seats that were won almost entirely on Layton’s personal popularity will remain orange minus "Bon Jack." Many of those seats were also taken at the expense of the Bloc Québécois now showing a revival in popularity.

In a revealing interview with CBC's chief correspondent Peter Mansbridge after the leadership convention, Mulcair totally ruled out any kind of co-operative arrangement with the Liberals going into the next election. Instead, Mulcair later told reporters the NDP will present itself as "the only party that can stand up to Stephen Harper in the next election."

The road to Mulcair's convincing Canadian voters of that is obviously long and anything but certain. But if he does succeed, we may have just witnessed the beginning of the end of the Liberal Party, and the Canadian political landscape will be reshaped as a choice between right and left.

Nothing would make Stephen Harper happier.