With 22 months to go to the US presidential election in 2020, the battle is hotting up.
Americans are beginning to assess who might be the opposition party nominee to challenge Donald Trump for control of the White House.
The election is being seen as a key moment for the US after four years of Mr Trump's divisive presidency, dominated by issues including race and a controversial foreign policy.
On the Democratic side, seven candidates have declared their plans, or are exploring doing so.
Kamala Harris
The Californian senator is seeking to become the first African American woman to hold the office.
The 54-year-old - the daughter of immigrants from Jamaica and India - is an outspoken critic of President Donald Trump's immigration policies.
She launched her campaign for the White House yesterday, Martin Luther King Day, by touting her experience as a prosecutor.
Senator Harris served as district attorney for San Francisco and attorney general of California.
Elizabeth Warren
The 69-year-old has represented Massachusetts in the Senate since 2013.
She is described as a progressive Democrat who is a strong critic of Donald Trump and a frequent sparring partner of the president.
He has repeatedly mocked her claim to have Native American heritage by calling her "Pocahontas," which has been taken as a slur.
Pocahontas was a Native American woman who lived in the 17th Century and is known in US history for her encounters with colonial settlers in Jamestown, in what is now Virginia.
Julian Castro
Mr Castro, 44, wants to become the first Hispanic president of the US.
He served as housing and urban development secretary in the Obama administration from 2014 to 2017.
Before that, he was mayor of San Antonio in Texas, and is often described as a rising star in the Democratic Party.
Kirsten Gillibrand
Ms Gillibrand has served in the US Congress as junior senator for New York since 2009.
She was previously a representative for New York in the House of Representatives.
The 52-year-old says that one of her priorities in Congress is to rebuild the US economy through more good-paying jobs and the creation of more small businesses.
Tulsi Gabbard
The Iraq War veteran is a congresswoman for Hawaii, having been deployed to Iraq in 2005.
She is the first Hindu member of Congress and its first Samoan American.
Ms Gabbard sits on the Foreign Affairs Committee, where she is able to influence US foreign policy.
If elected, the 37-year-old would be the youngest president in US history.
John Delaney
He served in the US House of Representatives for Maryland from 2013 to 2018.
The 55-year-old, who has Irish ancestry, was the first Democrat to announce his bid for the White House.
Richard Ojeda
The retired US army major served for 24 years and toured Korea, Honduras, Jordan, Haiti, Afghanistan and Iraq.
He was a senator for West Virginia from 2016 to 2019, but resigned earlier this month to focus on his presidential campaign.
There is one declared candidate for the Republican party.
Donald Trump
The current occupant of the White House assumed public office for the first time when he was sworn in as the 45th president in January 2017.
The wealthy New York businessman was elected on a slogan of 'Make America Great Again', defeating Hillary Clinton.
