Thousands of demonstrators gathered here on Saturday to protest against the xenophobic rhetoric and immigration policies of US President-elect Donald Trump who is set to take office on Friday.

About 2,000 demonstrators marched through the streets here under the slogan "We're here to stay" to protest against Trump's inauguration, as well as against candidates of the "extreme right" nominated for his Cabinet, EFE news reported.

Trump during his electoral campaign threatened massive deportation and ban on Muslims entering the US.

Al Sharpton, the organiser of the protest and a veteran civil rights leader, said Democrats in Congress needed to be sent a simple message: "Get some backbone."

"We march in the driving rain because we want the nation to understand that what has been fought for and gained, that you are going to need more than one election to turn it around," he added.

The demonstrators chanted "No justice, no peace" as they proceeded along the National Mall toward the Martin Luther King Jr. Memorial, Xinhua news agency reported.

The protest took place hours after the New York mogul traded accusations with US civil rights icon congressman John Lewis, who said Trump's presidency was "illegitimate".

"Lewis should spend more time on fixing and helping his district, which is in horrible shape and falling apart (not to mention crime infested) rather than falsely complaining about the election results," Trump said in a tweet.

Lewis is a veteran Democrat congressman representing Georgia.

Gustavo Torres, executive director of CASA, a Latino and immigrant advocacy group in Maryland, said his organisation exists to protect immigrants who contribute so much to this country and racism and intimidation will never be allowed to win the day.

Among the demonstrators' chief demands was protection for the young undocumented immigrants known as "dreamers" from being deported in case Trump revokes the executive orders outgoing President Barack Obama instituted to keep them from being sent back to their countries of origin.

The Deferred Action for Childhood Arrivals programme (DACA) protects more than a half-million young immigrants to the US from deportation while providing stability for them and their families.

Such is the case of Monica Camacho, an undocumented young woman who came to the US from Mexico in 2002 when she was 7-year-old, and joined the protest to make it clear that despite being afraid, she and others in her situation will keep fighting.

"This is our home. As immigrants we give a lot to this country. Our parents brought us here when we were little, and it is also the country of our parents," she told EFE.

"The community is worried, it's scared, but we're going to keep up the struggle anyway. There's always the fear of what can happen but we're sticking together," the young woman said.

The co-founder of the 'United We Dream' organisation, Cristina Jimenez, said she was "tremendously proud" that people of "conscience and compassion" around the country support DACA and families like hers and "the millions of immigrants and refugees that Trump has promised to attack".

"Together we will prepare our communities to oppose the agenda of hate, and we will win," she added.

In one of the most major protests here on January 21, the day after Trump's inauguration, more than 200,000 people are expected to join a Women's March, which organisers said will be the biggest protest in the history of the US.