Kamala Harris is ending her presidential bid and suspending her campaign, she announced Tuesday. In a statement, the Democratic senator from California explained she did not have enough funding to continue her run for the White House. Calling it "one of the hardest decisions of my life," and one she had made over the last few days, Harris said her campaign "simply doesn't have the financial resources we need to continue."

"I'm not a billionaire. I can't fund my own campaign," she said. "And as the campaign has gone on, it's become harder and harder to raise the money we need to compete."

She continued, "In good faith, I can't tell you, my supporters and volunteers, that I have a path forward if I don't believe I do. So, to you my supporters, it is with deep regret — but also with deep gratitude — that I am suspending my campaign today."

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In a sign of how challenging the lack of funding had become, aides said Tuesday that by the end of this week, former New York Mayor Michael Bloomberg will have spent on advertising alone about twice what Harris had raised for her own bid since the beginning of the year.

And in recent days, long-simmering turmoil between her team of professional consultants, mostly from California, and a faction represented by Harris' sister, Maya Harris, about how the campaign should proceed had boiled over into news reports. Maya Harris, a Democratic activist who also worked for Hillary Clinton's presidential campaign, has been at her sister's side for the duration of the campaign, serving as a top adviser.

Harris had begun her campaign in a commanding position, with a crowd of about 20,000 showing up at her kickoff rally in Oakland in late January. Her campaign at its inception seemed to show the capacity for growth, and she was viewed as a top-tier candidate. When she confronted Joe Biden about his stance on federal busing in the first presidential debate, it boosted her candidacy. But within days, her own views on busing became somewhat muddled.

Later, she struggled to articulate where she stood on health care and how she would pay for an overhaul of the health care system.

Harris, the third candidate in 48 hours to announce the end of her campaign, informed her staff Tuesday of her decision to suspend her campaign. After her statement, Harris posted a video of her statement on Twitter.

Biden responded to the news of her departure from the race by calling her a "first-rate intellect," a "first-rate candidate, and "a solid, solid person" who is "loaded with talent."

Julián Castro commended Harris and attacked some of the news outlets that recently reported stories that were critical of her campaign, noting "articles out of Politico, the New York Times, the Washington Post, that has basically trashed her campaign and focused on one small part of it, and I think held her to a different standard, a double standard has been grossly unfair and unfortunate."

Without Harris, Steve Bullock and Joe Sestak, the Democratic primary field now shrinks to 15 candidates.

In early November, Harris cut all of her field organizers in New Hampshire and shuttered her field offices there in order to focus her efforts in Iowa. At the time, she told CBS News she was "all in" on winning the Iowa caucuses and predicted she would "do very well" in the first contest of the 2020 Democratic presidential primary. Before the November debate, Harris had 131 staffers and 17 field offices in the state and had spent 45 days in Iowa, and she had even spent Thanksgiving in Iowa with her family.

Harris' husband tweeted a note of support for his wife.

Bo Erickson and Adam Brewster contributed to this report.