Former US vice president and democrat hopeful, Joe Biden scored victories in Texas, Massachusetts and seven other states on Super Tuesday, revitalising a presidential bid that was on the verge of disaster just days earlier.
Biden and Sanders, who have explicitly different visions for America’s future, battled it out in 14 states, and one US territory held a series of high-stakes elections that marked the most important day of voting in the party’s 2020 presidential nomination fight.
His rival Bernie Sanders, seized the biggest win, securing California where 415 delegates – more than any other state in the Democratic primary – were up for grabs.
The win gave Sanders a much-needed boost after a revivified Biden swept the southern states of Virginia, North Carolina, Alabama, Arkansas, Tennessee and Oklahoma.
Exit polls indicated that the Vermont senator had an approximate 15-point lead, though final results may not be confirmed for days.
In recent weeks, Democratic leaders and officials warned that a fragmented result on Super Tuesday is likely to put Sanders on a runaway path to the nomination.
However, on Tuesday night, Sanders put on the bravest face he could.
He said: “I am excited about where we are. We have come a long, long way, now let’s go on to the White House.”
Though he didn’t mention the former vice president by name, he criticised him over his vote for the war on Iraq and his support for “disastrous trade agreements which cost millions of good-paying jobs.
“You cannot beat Trump with the same-old, same-old kind of politics,” Sanders declared.
Meanwhile, billionaire and New York’s former mayor Mike Bloomberg did not see his $500m gamble pay dividends after failing to secure any delegates.
Bloomberg, who has funnelled huge sums of his fortune into his own campaign, won the US territory of American Samoa, which has just six delegates in play. He failed to secure delegates in Virginia, where he spent nearly $18m on advertising.
Exit polls also indicated Bloomberg was struggling to clear the 15% threshold required to net delegates in North Carolina, where he is reported to have spent a futher $17m and built a large field operation.
Super Tuesday is the most significant voting day of the Democratic presidential primary race, with millions of voters across the US casting their ballots for the candidate they want to see take on Donald Trump in the November election.
It remains unclear whether Biden or Sanders will establish a controlling advantage. The uncertainty could pave the way toward a contested convention, something the party has not seen since 1952.
Who are the candidates at the core of the race?
Born in Scranton, Pennsylvania, Biden studied at the University of Delaware before graduating with a degree in law. He became a lawyer in 1969 and was elected to the New Castle County Council in 1970.
He served six terms as senator in Delaware where he was first elected in 1972, becoming the sixth-youngest senator in American history.
During his first years in the Senate, Biden focused on legislation regarding consumer-protection and environmental issues and called for greater accountability in government.
In mid-1974, he was named one of the 200 Faces for the Future by Time magazine, in a profile that mentioned what had happened to his family and characterised him as "self-confident" and "compulsively ambitious".
Mr Biden served as vice president in the Obama administration during the passage of the Affordable Care Act, and health care remains a top priority for him. It’s an issue he often discusses in the context of his family’s personal tragedies: He lost his first wife and a baby daughter in a car accident in 1972, and in 2015, his son Beau Biden died of brain cancer.
Biden has criticised the Medicare for All plans being pushed by Sanders and Warren as a misguided effort to dismantle the Affordable Care Act (ACA), Obama's signature healthcare law.
As an alternative, Biden has promised to "build on" the act, popularly known as Obamacare, by adding a public option that would leave the current private insurance system in place.
His healthcare plan, estimated to cost $750bn over 10 years and paid for partly by higher taxes on the wealthy, would let people enrol in a paid government healthcare plan as an alternative to private insurance.
The proposal would also expand the ACA's subsidies for private policies, making them more generous and extending them to more people.
As a former chairman of the Senate Foreign Relations Committee, Biden also speaks passionately about asserting and defending America’s role as a leader on the global stage.
He has consistently led the Democratic pack in national polls, but has encountered tough competition from more progressive wings of the party, embodied by Senators Bernie Sanders and Elizabeth Warren, both of whom have promised sweeping institutional changes.
While his Democratic competitors have struggled to appeal to black voters, analysts say African Americans have long been a pillar of support for Biden, especially in his home state of Delaware, which is 38 percent black, and where he served as a US senator for nearly four decades.
Sanders was born in 1941, into a working-class Jewish family and raised in Brooklyn, New York.
He attended Brooklyn College before graduating from the University of Chicago in 1964. Sanders became interested in politics at an early age and as a student, he was an active protest organiser for the Congress of Racial Equality, as well as for the Student Nonviolent Coordinating Committee during the civil rights movement.
After settling in Vermont in 1968, he ran third-party political campaigns in the early to mid-1970s. As an independent, he was elected mayor of Burlington in 1981 and re-elected three times.
He was elected to the House of Representatives in 1990, representing Vermont's at-large congressional district; he later co-founded the Congressional Progressive Caucus. He served as a US Representative for 16 years before being elected to the U.S. Senate in 2006; he was re-elected to the Senate in 2012 and 2018.
An advocate of social democratic and progressive policies, Sanders is known for his opposition to economic inequality and neoliberalism.
With an anti-establishment style that has changed little over five decades, Sanders has attracted a loyal fan base.
Running for president a second time, he is one of the most-well known candidates in the race.
The Sanders plan envisions a future where all Americans have health coverage and pay nothing out of pocket when they visit the doctor. His Medicare for All Act, describes a benefit package that is more generous than what other single-payer countries, like Canada, currently offer their residents. It also includes new income taxes on both employees and employers.
Sanders, who has referred to President Donald Trump's immigration policies as "heartless," wants to offer a pathway to citizenship to most undocumented immigrants and supports comprehensive immigration reform.
Sanders has also called for restructuring Immigration and Customs Enforcement (ICE), stating, "We must not be about tearing small children away from their families."