Heirs to the family business, staunch defenders of their presidential father, avid big game hunters, self-described "brutes" — these are the labels commonly used to describe the eldest sons of U.S. President Donald Trump, Eric and Donald Jr., who on Tuesday will visit Vancouver for the grand opening of a new luxury hotel.

The event, which is expected to draw crowds of protesters, is the second launch of a Trump-branded property the brothers have overseen since they took the helm of the family business.

The president announced he was handing control of the Trump Organization to his eldest sons to avoid conflicts of interest, before he took office. Eric, 33, and Donald Jr., 39, are now executive vice-presidents of the company that owns hotels, buildings, golf courses, and casinos. It also licences the Trump name to be used for business ventures and properties.

Trump's oldest daughter, Ivanka, who had also previously worked for the company has also stepped aside and moved to Washington, D.C. Her husband Jared Kushner is an adviser to her father.

'Much will be required'

Donald Trump Jr. mused about running for mayor of New York City following the Republican National Convention. (Alex Wong/Getty)

Eric and Donald Jr. played a prominent role in their father's bid for the presidency, praising him as an honourable businessman and devoted parent. They dubbed themselves "the brutes" on the campaign trail, while the rival Hillary Clinton campaign nicknamed them "the Storm Troopers," because of the way they slick back their hair and their resemblance to elite First World War German soldiers, according to a Vanity Fair profile.

The brothers defended their father against attacks, each of them describing him as their best friend in speeches delivered at the Republican National Convention in July 2016.

"To whom much is given, much will be required," Eric said of his father. "This is the very belief that compelled my father to make this great sacrifice, to run for the most powerful yet unforgiving office in the world. There is no greater calling, there is no more selfless an act."

Donald Jr. joined his father's company in 2001 after graduating from the University of Pennsylvania. Eric followed suit and joined the Trump Organization once he had earned a degree in finance and management from Georgetown University in 2006. He also started the Eric Trump Foundation, which has raised more than $16 million US for St. Jude's Children Research Hospital of Tennessee. Both brothers also played a role on their father's reality show The Apprentice.

Donald Jr., was 12 when his father and mother, Ivana, divorced. Eric was six. The brothers and their sister Ivanka were largely raised by their mother. In a 2016 interview with the Atlantic, Donald Jr. said his father taught them the family business at an early age.

"He made time for us, but it was always on his terms," he said, noting they often accompanied their father to construction sites and the office.

Scrutiny on the campaign trail

Following the RNC, Donald Jr. mused about a career change to public service. He told CNN's State of the Union that he was keeping his options open and was considering running for mayor of New York City against incumbent Bill de Blasio in 2017.

"Well, you know, listen, I had a good time up there," he told CNN of his speech at the RNC. "I'm really frustrated with what's going on in this country. If [running for office] is how I can pay back and give something back … but right now I'm more concerned with getting my father in there."

Donald Trump Sr. later appeared on Fox News, saying his son probably wouldn't run for office.

"Running for mayor of New York City — all right, I don't see that happening. I don't think that'll happen."

The brothers faced close scrutiny when stumping for their outspoken father. Photos of Eric and Donald Jr. posing with the bodies of an elephant and leopard during a hunting trip in Africa spurred criticism from animal rights activists. The brothers defended their trips, saying the hunting was conducted lawfully and was a tradition they learned from their grandfather.

Donald Trump Jr. tweeted this campaign ad on Sept. 19. It was later removed from Twitter. (Twitter)

Donald Jr. encountered further criticism when he compared Syrian refugees and the candy Skittles.

"If I had a bowl of skittles and I told you just three would kill you. Would you take a handful? That's our Syrian refugee problem," he tweeted in September 2016.

Critics said the analogy, likening human life to candy, was insensitive and inappropriate. Trump defended himself, saying at a campaign stop in Boise, "I am surprised by the reaction simply because it is a metaphor for risk."

Eric and his wife Lara Yunaska live in Manhattan. Donald Jr. and his wife Vanessa also live in New York City with their five children.