Democratic White House hopeful Kamala Harris is dropping out of the presidential race.The California senator's campaign seemed full of promise when it launched in January, but she struggled to make headway in a crowded field.In November her cash-strapped operation laid off staff at its Baltimore HQ, in New Hampshire and in her home state.The 55-year-old, a fierce critic of President Donald Trump, was once seen as a rising star within the party.But she could not cement her fleeting position in the top tier of candidates alongside Joe Biden, Bernie Sanders and Elizabeth Warren.Ms Harris entered the race as a leading contender, launching her bid for the White House to a crowd of more than 20,000 in Oakland, California, at the beginning of the year.She reached double-digits in the polls after attacking Mr Biden on the issue of race during a live TV debate in June, but began to lag in recent months.

To my supporters, it is with deep regret””but also with deep gratitude””that I am suspending my campaign today.

But I want to be clear with you: I will keep fighting every day for what this campaign has been about. Justice for the People. All the people.https://t.co/92Hk7DHHbR— Kamala Harris (@KamalaHarris) December 3, 2019

"I've taken stock and looked at this from every angle, and over the last few days have come to one of the hardest decisions of my life," Ms Harris said in an email to supporters on Tuesday."My campaign for president simply doesn't have the financial resources we need to continue."I'm not a billionaire. I can't fund my own campaign. And as the campaign has gone on, it's become harder and harder to raise the money we need to compete."She held a conference call with staff earlier in the day to inform them of her decision.Her husband, Douglas Emhoff, tweeted a message of support to her after the announcement.

I”™ve got you. As always.❤️ pic.twitter.com/5OJDT3cDfw

— Douglas Emhoff (@douglasemhoff) December 3, 2019

After a tweet by President Trump appeared to mock her departure from the race, Ms Harris responded with a scathing tweet referencing his possible impeachment trial in the Senate. On Tuesday, a Democrat-led investigation in the House of Representatives said there was "overwhelming" evidence to impeach Mr Trump for misconduct in office. However no formal charges have yet been laid.

Don”™t worry, Mr. President. I”™ll see you at your trial. https://t.co/iiS17NY4Ry

— Kamala Harris (@KamalaHarris) December 3, 2019

Mr Biden was among those who paid tribute to his former rival.He said: "My reaction is she is a first-rate intellect, a first-rate candidate."He added: "I have mixed emotions about it because she is really a solid, solid person, and loaded with talent."I'm sure she's not dropping out on wanting to make the changes she cares about."Other candidates were also quick to pay tribute.

My dear friend @KamalaHarris is a trailblazer. I've loved serving with her in the Senate and every moment we've run into one another on the trail. Her campaign broke barriers and did it with joy. Love you, sister. pic.twitter.com/HzLXw88NrM

— Cory Booker (@CoryBooker) December 3, 2019

I am stunned that Kamala Harris is suspending her campaign. She is one of my favorite people to share time with on the trail. So warm, smart, fiery and a true public servant. She offered my family help and guidance when she didn”™t need to. Kamala I will see you soon.

— Andrew Yang🧢 (@AndrewYang) December 3, 2019

Kamala is a good friend and incredibly strong public servant. Sometimes campaigns can tear friendships apart but we have grown closer. Her good work will continue.

— Amy Klobuchar (@amyklobuchar) December 3, 2019

Ms Harris, a former San Francisco attorney-general, had already qualified for the next round of Democratic debates, to be held later this month in her home state.But polling showed her in the single digits in national surveys as well as those conducted in early-voting states.After initially raising $12m in the first three months of her campaign, she failed to harness momentum.