WASHINGTON — A few little words from Hillary Clinton have turned a Canadian oil project into an election issue, possibly in two countries.

First she came out against the Keystone XL pipeline: "I oppose it," she said Tuesday.

Then she went further. The presumed frontrunner in the U.S. presidential election race later referred to Canadian oil in a tweet as the "continent's dirtiest fuel."

Clinton's long-awaited position statement almost certainly makes the oil pipeline a U.S. election issue in 2016. It creates a clear partisan split: the candidates from the Democratic party are now aligned against it, the Republicans are solidly in favour, and they've immediately pounced on her words.

It's a scenario the Canadian government hoped to avoid. At every opportunity, its diplomats in Washington had tried to keep the Alberta-to-Texas pipeline from tumbling into a partisan chasm.

Visiting ministers made sure to meet with supporters from both parties. Ambassador Gary Doer could barely mention Keystone without pointing out how some Democrats also supported it.

But Tuesday offered a different preview of 2016: Republicans and Democrats bashing each other over the Alberta-Texas pipeline, and the Canadian government unhappily wedged between them.

A recent poll illustrates why it's a risky proposition for a Canadian politician to side with Republicans in a fight — the Ipsos survey last month suggested Canadians favour Democrats by a crushing margin of nearly 40 per cent.

And in this fight, there's no doubt where Republicans stand.

One candidate happened to be in a Fox News studio when the decision was announced. Ohio Gov. John Kasich ridiculed the decision as a sop to liberal groups during the Democratic primary.

Barely an hour later, another Republican was using the issue to sign up supporters. Sen. Marco Rubio's campaign distributed a signup page that listed the pipeline as one reason her energy policy is outdated: "[It's] a throwback to yesterday, before the 21st century energy revolution that is making America the world's greatest energy producer."

Jeb Bush tweeted: "[Clinton] favors environmental extremists over U.S. jobs." Bush has accused Democrats of insulting Canada, and suggested he'd have to repair relations with the northern neighbour.

Fox News piled on.

It ran a clip of Clinton seemingly expressing support for Keystone a few years ago. Her own former department has concluded it would reduce pollution, compared to transporting oil by rail. But climate activists note those State Department assessments were based on now-irrelevant high oil prices.

The Harper campaign issued a careful statement Tuesday that defended the project but avoided mentioning Clinton's name.

In the current Canadian election campaign, the pipeline has already played a cameo role. It's come up in both leaders' debates. But the politics of the issue is a bit more complex in Canada.

Of the three big national parties, two support Keystone:

—The Conservatives want it approved. The government has spent millions on ads in the U.S. to help promote it. Prime Minister Stephen Harper blames the American administration for political foot-dragging.

—The Liberals also want it approved. But they accuse the Harper government of making a mess of the file. They say its antagonism toward environmental issues put a target on Canadian oil.

—The NDP opposes the project, but not on climate-change grounds. It wants more oil refined in Canada.

The Calgary-based pipeline company raised different arguments its reaction Tuesday: environmental, economic, and political.

In a statement, TransCanada Corp. mentioned the thousands of jobs from the pipeline; the fact that its contents simply displace also-dirty Venezuelan oil in U.S. refineries; and the higher emissions from train transport.

The company even referred to a poll — an industry study that showed two-thirds of Americans believe the years-long delay has hurt the economy.

Polls have regularly shown Americans tend to support Keystone.

But the intensity of that support is an open question. An NBC poll earlier this year said almost as many Americans had no opinion as the number who supported it. It said 41 per cent favoured Keystone, 20 per cent opposed it, and 37 per cent didn't answer or didn't know enough about it.

If Keystone has been a recurring theme in U.S. politics for years, it's rarely been a No. 1 issue. That was illustrated late Tuesday when Clinton's announcement was the No. 3 story on the Politico site, after Pope Francis' arrival in the U.S. and talk of another possible U.S. government shutdown.

The Republicans tried making it an issue in 2012. At the time, the Democratic candidate had no official position on the pipeline. President Barack Obama still hasn't announced his decision.

Yet Obama beat Mitt Romney, who promised: "I will build that pipeline if I have to myself."

Alexander Panetta, The Canadian Press.

Keep reading