Repeal this, legislate that, nominate them.

U.S. presidential candidates Hillary Clinton and Donald Trump can make all the campaign promises they want, but they won't be able to accomplish much without Congress.

While the fight for the White House gets all the sizzle in this fiery election season, Canadian interests are also watching the down-ballot races as our superpower neighbour to the south — our biggest trading partner — shuffles seats in the Senate and the House of Representatives. More than 400,000 people flow back and forth across the Canada-U.S. border each day.

At stake for Canada? Anything from trade pacts to ease of cross-border travel, taxes on goods, a potentially lucrative project for Hydro-Québec and climate change co-operation.

Traffic makes its way from Windsor, Ont., to the Ambassador Bridge that connects Canada to the United States. In the dwindling days of the current Congress, a border pre-clearance agreement has stalled. (Mark Spowart/Canadian Press)

Whoever takes over the Oval Office, just as important to Canadians will be what the partisan composition is in the U.S. chambers.

"It's what I've been telling Canadians for a long time," says Maryscott Greenwood, senior advisor with the non-partisan Canadian American Business Council. "I know everybody's obsessed with Trump-Clinton, but really, let's also think about the Congress."

Colin Robertson, a former diplomat and vice-president of the Canadian Global Affairs Institute, notes that as a general principle, "Democrats are less sympathetic on trade and bring in more Buy America legislation." But both Clinton and Trump have offered protectionist views on trade policies.

Either way, it's a moot point "because you work with whoever's there," he says.

How Congress approves future judicial appointments will matter because the U.S. Supreme Court, while not holding jurisdiction in Canada, often makes decisions that are of interest to Canada.

How we approach things is so closely linked — because of our economy, our environment — that we tend to move in tandem. - Colin Robertson, vice-president of the Canadian Global Affairs Institute

"How we approach things is so closely linked — because of our economy, our environment — that we tend to move in tandem," Robertson says.

While it appears to be an increasingly distant possibility that the Democrats will be able to flip the Lower House to their control — requiring at least 30 seats from the Republicans — a Democratic-majority Senate looks within reach.

Were that to happen, Greenwood notes that the Upper House would have two members from Washington State, Democratic senators Patty Murray and Maria Cantwell, in powerful committee positions.

As for why that matters to Canadian trade policy?

Both senators have played active roles in matters to do with the Port of Seattle, arguing that Canadian ports have unfair advantages over U.S. ports.

The senators have tried to introduce legislation to slap a fee on all containers entering the U.S. via Canadian and Mexican ports.

"A border tax on all cargo," as Greenwood describes it. "And it hasn't seen the light of day or been passed in[to] law so far because Murray and Cantwell weren't senior enough" to be able to broker the kinds of deals they might have coveted.

Container ships sit moored at the Port of Seattle, which is in the constituency of two Democratic senators for Washington state who say Canadian ports have an unfair advantage over U.S. ports. (Elaine Thompson/Associated Press)

TPP up in the air

Then there's the Trans-Pacific Partnership.

The largest regional trade pact in history includes Canada, the U.S. and 10 other signatories, but if Washington doesn't want anything to do with it, Canada probably won't want to either.

"It would be in Canada's interests not to try navigating the Asian trade pond by itself," says Geoffrey Hale, a policy expert on U.S.-Canada relations with the University of Lethbridge. "It's a lot easier to slipstream behind the Americans in these waters than to try to cobble together alliances" with the Pacific Rim countries involved.

Clinton has denounced TPP, which she at one time hailed as a "gold standard" in trade agreements. Trump exhibits a rather un-Republican opposition to free trade, slamming it as "the death blow for American manufacturing."

Delegates protesting against the Trans Pacific Partnership (TPP) trade agreement hold up signs at the Democratic National Convention in Philadelphia on July 25, 2016. (Mark Kauzlarich/Reuters)

Obama's fast-track on TPP was achieved with Republicans in the House and Senate, not within his own party.

Greenwood isn't betting on the prospect that Obama will be able to push its passage through a lame-duck Congress, believing TPP will instead "wither on the vine."

Border bill stalled

Likewise on the climate change front, Hale says the likelihood of coherent climate change legislation coming out of Congress in the coming session is slim. Hale says the "modest Democratic majority" projected for the Senate wouldn't give Clinton much room to manoeuvre.

"The [Canadian] government would be absolutely insane to take a very aggressive, unilateral approach on climate change if the United States was doing absolutely nothing," Hale says.

A Canada-U.S. border pre-clearance agreement also has been stalled. Passage of the bill, which in Canada received first reading in the House of Commons in June, would expedite commerce and allow pre-cleared travellers to skip long customs lines.

Although the deal has bipartisan support in the U.S., there's precious time left to pass the law. And once the new session of Congress begins, "you've got to get started from go again," Greenwood says.

Canadian interests are hot topics in local congressional races this year.

In New Hampshire, voters worry about the "Northern Pass," a $1.7-billion joint proposal from Hydro-Québec and New England's Eversource to export 1,000 megawatts of hydro power to the northeastern U.S. The controversial 309-kilometre high-transmission line would cut a swath through idyllic New Hampshire landscapes. Republican Senate candidate Dolly McPhaul opposes the plan, which would run through her district, and has focused her campaign on the issue.

In Alaska last month, Senate candidates on public radio debated how B.C. mineral mining upstream was affecting water flowing into southeast Alaska and threatening the state's fishing industry. Republican senator Lisa Murkowski faced a grilling from independent Margaret Stock on creating an international commission to look into the matter.

Robertson, the former diplomat, notes that when the U.S. election ends, Canada's wheeling and dealing only just begins.

"We have permanent interests for whoever's there. We work with whoever we can to find our way in," he says, adding, "For Canada, it's a permanent campaign."