On July 15, 2019, the nonprofit Biden Cancer Initiative announced it would cease operations for the foreseeable future.
Biden and his wife left the initiative's board in April as an ethics precaution before starting his presidential campaign.

In September 2019, it was reported that President Trump had pressured Ukrainian president Volodymyr Zelensky to investigate alleged wrongdoing by Biden and his son Hunter Biden.
Despite the allegations, as of September 2019, no evidence has been produced of any wrongdoing by the Bidens.
The media widely interpreted this pressure to investigate the Bidens as trying to hurt Biden's chances of winning the presidency, resulting in a political scandal and Trump's impeachment by the House of Representatives.

Beginning in 2019, President Trump and his allies falsely accused Biden of getting the Ukrainian prosecutor general Viktor Shokin fired because he was ostensibly pursuing an investigation into Burisma Holdings, which employed Hunter Biden.
Biden was accused of withholding $1 billion in aid from Ukraine in this effort.
In 2015, then-Vice President Biden pressured the Ukrainian parliament to remove Shokin because the United States, the European Union and other international organizations considered him corrupt and ineffective, and in particular was not assertively investigating Burisma.
The withholding of the $1 billion in aid was part of this official policy.

Throughout 2019, Biden generally led his Democratic rivals in national polls and was considered the frontrunner in the Democratic presidential primaries.
Despite this, he finished fourth in the Iowa caucuses, and eight days later, fifth in the New Hampshire primary.
He performed better in the Nevada caucuses, reaching the 15% required for delegates, but still was behind Bernie Sanders by 21.6 percentage points.
Making strong appeals to black voters on the campaign trail and in the South Carolina debate, Biden won the South Carolina primary by more than 28 points.
After the withdrawals and subsequent endorsements of center-left candidates Pete Buttigieg and Amy Klobuchar, he made large gains in the March 3 Super Tuesday primary elections.
Biden won 18 of the next 26 contests, including Alabama, Arkansas, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas, and Virginia, putting him in the lead overall.
Elizabeth Warren and Mike Bloomberg soon dropped out, and Biden expanded his lead with victories over Sanders in four states (Idaho, Michigan, Mississippi, and Missouri) on March 10.

With the suspension of Sanders's campaign on April 8, 2020, Biden became the Democratic Party's presumptive nominee for the presidential election.
On April 13, Sanders endorsed Biden in a live-streamed discussion from their homes.
Former President Barack Obama endorsed Biden the next day.
In March 2020, Biden committed to choosing a woman as his running mate.
In June, Biden met the 1,991-delegate threshold needed to secure the party's presidential nomination.
On August 11, he announced Senator Kamala Harris of California as his running mate, making her the first African American and South Asian American vice-presidential nominee on a major-party ticket.

On August 18, 2020, Biden was officially nominated at the 2020 Democratic National Convention as the Democratic Party nominee for president in the 2020 election.

On August 20, seventy Republican former senior national security officials announced they would vote for Biden, saying Trump was "unfit to lead during a national crisis".
On July 15, 2019, the nonprofit Biden Cancer Initiative announced it would cease operations for the foreseeable future. Biden and his wife left the initiative's board in April as an ethics precaution before starting his presidential campaign.
In September 2019, it was reported that President Trump had pressured Ukrainian president Volodymyr Zelensky to investigate alleged wrongdoing by Biden and his son Hunter Biden. Despite the allegations, as of September 2019, no evidence has been produced of any wrongdoing by the Bidens. The media widely interpreted this pressure to investigate the Bidens as trying to hurt Biden's chances of winning the presidency, resulting in a political scandal and Trump's impeachment by the House of Representatives.
Beginning in 2019, President Trump and his allies falsely accused Biden of getting the Ukrainian prosecutor general Viktor Shokin fired because he was ostensibly pursuing an investigation into Burisma Holdings, which employed Hunter Biden. Biden was accused of withholding $1 billion in aid from Ukraine in this effort. In 2015, then-Vice President Biden pressured the Ukrainian parliament to remove Shokin because the United States, the European Union and other international organizations considered him corrupt and ineffective, and in particular was not assertively investigating Burisma. The withholding of the $1 billion in aid was part of this official policy.
Throughout 2019, Biden generally led his Democratic rivals in national polls and was considered the frontrunner in the Democratic presidential primaries. Despite this, he finished fourth in the Iowa caucuses, and eight days later, fifth in the New Hampshire primary. He performed better in the Nevada caucuses, reaching the 15% required for delegates, but still was behind Bernie Sanders by 21.6 percentage points. Making strong appeals to black voters on the campaign trail and in the South Carolina debate, Biden won the South Carolina primary by more than 28 points. After the withdrawals and subsequent endorsements of center-left candidates Pete Buttigieg and Amy Klobuchar, he made large gains in the March 3 Super Tuesday primary elections. Biden won 18 of the next 26 contests, including Alabama, Arkansas, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas, and Virginia, putting him in the lead overall. Elizabeth Warren and Mike Bloomberg soon dropped out, and Biden expanded his lead with victories over Sanders in four states (Idaho, Michigan, Mississippi, and Missouri) on March 10.
With the suspension of Sanders's campaign on April 8, 2020, Biden became the Democratic Party's presumptive nominee for the presidential election. On April 13, Sanders endorsed Biden in a live-streamed discussion from their homes. Former President Barack Obama endorsed Biden the next day. In March 2020, Biden committed to choosing a woman as his running mate. In June, Biden met the 1,991-delegate threshold needed to secure the party's presidential nomination. On August 11, he announced Senator Kamala Harris of California as his running mate, making her the first African American and South Asian American vice-presidential nominee on a major-party ticket.
On August 18, 2020, Biden was officially nominated at the 2020 Democratic National Convention as the Democratic Party nominee for president in the 2020 election.
On August 20, seventy Republican former senior national security officials announced they would vote for Biden, saying Trump was "unfit to lead during a national crisis".
Joe Biden