Massachusetts Senator Elizabeth Warren has dropped out of the Democratic race for US president.

In a statement on Thursday, she said: "I'm suspending our campaign for president."

In a call with campaign staff she added: "I know how hard all of you have worked. So from the bottom of my heart, thank you for everything you have poured into this campaign.

"I know that when we set out, this was not what you ever wanted to hear. It is not the call I ever wanted to make.

"But I refuse to let disappointment blind me - or you - to what we've accomplished.

"We didn't reach our goal, but what we have done together - what you have done - has made a lasting difference."

"So if you leave with only one thing, it must be this: Choose to fight only righteous fights, because then when things get tough, and they will, you will know that there is only one option ahead of you: Nevertheless, you must persist."

She is the latest high-profile name to leave the Democratic ticket to face Donald Trump in November.

Billionaire Mike Bloomberg dropped out on Wednesday and endorsed former vice-president Joe Biden.

Mr Biden took a big step toward becoming the nominee on so-called 'Super Tuesday' - winning delegates in Alabama, Arkansas, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee and Virginia.

Senator Bernie Sanders also won a number of key states - including California.

Senator Elizabeth Warren was a distant third and symbolically lost the primary vote in her home state of Massachusetts.

Both Mr Biden and Mr Sanders are now likely to face a long fight for delegates in the remaining states ahead of the Democratic National Convention in the summer, where the party's candidate to face Mr Trump in November will be chosen.

Two other prominent Democrats - Pete Buttigieg and Amy Klobuchar - earlier dropped out of the race and endorsed Mr Biden.