ARLINGTON, the United States, March 3 (Xinhua) -- Polling stations opened on the U.S. East Coast Tuesday morning, kicking off the so-called "Super Tuesday" primaries of the 2020 presidential election.

In Virginia, one of 14 U.S. states scheduled to hold votes this day, only candidates running for the Democratic nomination for the White House are on the ballot, as the state's Republican Party has canceled its primary to throw full support behind sitting President Donald Trump.

Other states, including populous California and Texas, are scheduled to hold both Republican and Democratic primaries, some of which began hours later because of time differences.

Trump, who's facing no major challenges in the Republican Party, is expected to win the GOP primaries, while on the Democratic side there are still five vying for the party's nomination to challenge the incumbent.

After caucuses and primaries in four early voting states, Senator Bernie Sanders of Vermont is currently leading in the Democratic field with the most pledged delegates to the Democratic National Convention (DNC), followed by former Vice President Joe Biden.

At a polling place in Arlington, Max Blake told Xinhua that he voted for Sanders despite Biden's resurging momentum triggered by a big victory in the South Carolina Democratic primary several days ago.

The Virginia voter also said he is aware of an ongoing tussle between the Democratic Party's progressive candidates and the moderate bloc but that he believes they will eventually unite for the race against Trump.

Besides Sanders and Biden, former New York City Mayor Michael Bloomberg, Senator Elizabeth Warren of Massachusetts, and U.S. Congresswoman Tulsi Gabbard of Hawaii are also in the Democratic primary race.

Bloomberg, who is making his ballot debut on Tuesday, traded barbs with Trump on Twitter in the morning.

On Super Tuesday, 1,357 pledged delegates to the DNC or a third of the total will be up for grabs.

To win the Democratic presidential nomination, a candidate must receive support from a majority of all the 3,979 pledged delegates on the first ballot of the national convention: 1,991 delegates.

In other words, the Super Tuesday primaries will not determine who will become the Democratic presidential nominee. However, Super Tuesday could offer indicators for how the rest of the primaries might play out.

"This is the first time that a large number of states in different regions of the country all vote on the same day," Clay Ramsay, a senior research associate at the Center for International and Security Studies at University of Maryland, told Xinhua.

"The four previous state caucuses and primaries each had their own local flavor. They can't tell us what Democrats across America are thinking," Ramsay said. "Super Tuesday will get us much closer to seeing that."

Former Democratic presidential candidate Andrew Yang, in a tweet on Tuesday morning, called it "an enormous day in the presidential race."

"A lot of questions will be answered in the next 36 hours," he added.

Polls close between 7 p.m. and 8 p.m. local time, depending on the state.