Texas Democrat Julian Castro has endorsed Massachusetts senator Elizabeth Warren to be their party’s 2020 presidential nominee to challenge Donald Trump in November.

Castro, a former US secretary for Housing and Urban Development under Barack Obama, suspended his own campaign for the presidency on 2 January having failed to qualify for the last two primary debates or whip up momentum in the polls and wasted little time in giving his backing to Warren.

“There’s one candidate I see who’s unafraid to fight like hell to make sure America’s promise will be there for everyone, who will make sure that no matter where you live in America or where your family came from in the world, you have a path to opportunity, too,” Castro said in a video announcing the endorsement posted on social media.

An ex-mayor of San Antonio, Castro uses the short clip to praise the “strong women” who have shaped his life, notably his grandmother Victoria, who emigrated to the US when she was seven years old.

He is seen paying a visit to Warren at her home as the pair sit down in her kitchen and bond over a cup of tea, agreeing the need to spread a message of hope on the campaign trail.

“I’m not running for president just to go live in the White House,” the former Harvard law professor says over a montage of her meeting friendly voters. “I’m running for president to make change for our families all across this country. To make change so that everybody has real opportunity in this country.”