Voting is underway in Virginia and a slew of other American states on Super Tuesday, the most pivotal day of the presidential primary season, with front runners Hillary Clinton and Donald Trump hoping for big wins to clinch their party nominations.
Millions of Americans voted in a series of primaries and caucuses in a dozen states, stretching from Massachusetts and Virginia on the east coast to Texas and all the way to Alaska.
The first polls close at 7pm Eastern time (8am Wednesday Singapore time) in Georgia, Vermont and Virginia. Most in Texas, the biggest prize in terms of delegates, close an hour later.
Polling stations in Virginia opened at 6am on Tuesday US time with some centres attracting lines from the start.
At the Lake Braddock Secondary School in Fairfax, Virginia, there was a steady stream of voters coming in to cast their ballots. Election workers at one station estimated that they were getting two votes per minute - unusually high for a primary election.
Ms Elaine Homstad, chief election officer for the Fairfax County Election Board, said: "This looks more like a general election than a primary. Looks like we're going to have a very busy general election."
One precinct was reportedly even running low on ballots.
Voters supporting various candidates said they made a point of showing up because a lot was at stake in this election.
Mr John Young, 60, a purchasing agent, said: "I voted for Donald Trump because I believe he is the only candidate who can win the election in the fall. Conservatives have been losing for years at the national level and he is the candidate that can bring in Democrats and win."
Some 13 states and one American territory will hold election activities today - the single largest day of voting in the election primary process.
All eyes will be on the front runners of the two parties - billionaire Donald Trump and former secretary of state Hillary Clinton. Both of them are headed into Super Tuesday following dominant performances. Mr Trump won the Republican Nevada caucuses last week in a landslide while Mrs Clinton beat Senator Bernie Sanders in the South Carolina Democratic Primary by nearly 50 points.
Both will be looking to consolidate their leads today with nearly one quarter of the available delegates up for grabs.
The stakes are especially high in the Republican Party, which is in the unusual position of having a front runner that party leaders oppose. Mr Trump, a political outsider, has won three out of the first four races and party leaders are now working to dent his momentum.
"March 1 - indeed with over 600 delegates - has the potential to put such a gap between him and everyone else in the field," said Republican Party insider Ben Ginsberg, a lawyer who served as national counsel to the George W Bush campaign in 2000 and 2004.
"He will be going to his strengths, which are massive amounts of earned media and the money resources he has to buy more advertising to knock everybody else out. His claim on March 2 will be, 'I won more states than anybody else; I am the winner.'"
The second and third-placed candidates, Senators Marco Rubio and Ted Cruz have spent much of the week heading into Super Tuesday ganging up on Mr Trump, portraying him as a con artist and an unreliable conservative. They will be looking to Super Tuesday's results to see if the effort is paying off.
Over on the Democratic Party side, few are giving Mr Sanders much chance of winning the nomination now and he will have to produce some significant upsets across the southern states voting today to change minds.