WASHINGTON, March 10 (Xinhua) -- Six U.S. states are scheduled to hold primaries on Tuesday for voters to select their prefered presidential candidate this year.
The states that are voting or are about to vote are Idaho, Michigan, Mississippi, Missouri, North Dakota, and Washington.
Sitting President Donald Trump is expected to win the Republican primaries as he faces no major challenges in the party.
On the Democratic side, former U.S. Vice President Joe Biden and Senator Bernie Sanders of Vermont are locked in a one-on-one battle for the party's presidential nomination.
The two candidates are paying much attention to Michigan, a battleground state that awards 125 pledged delegates to the Democratic National Convention (DNC), scheduled for July in Milwaukee, Wisconsin.
According to a poll released on Monday, Biden, a 77-year-old moderate political veteran, is coming into Michigan's Democratic primary with a 24-point lead over Sanders, a 78-year-old progressive.
Biden has 51 percent support in Michigan, according to a Detroit Free Press survey, compared to 27 percent for Sanders. The poll has a margin of error of 4.9 percentage points.
In 2016, Sanders won Michigan in the Democratic primary with an upset victory against Hillary Clinton, after polls showed that he had trailed well behind the former U.S. secretary of state.
Sanders still leads among voters between the age of 18 and 34, at 58 percent support compared to Biden's 17 percent, according to Monday's poll.
Michigan is also a crucial state in the November election: Trump won the state by just over 10,000 votes in 2016, becoming the first Republican to win it since 1988.
Tuesday's contests come a week after Super Tuesday's Democratic primaries, in which Biden won 10 of the 14 states voting that day, while Sanders won the other four.
Biden also leads Sanders in pledged delegates with 670 to 574, as of Tuesday morning.
U.S. Congresswoman Tulsi Gabbard of Hawaii is still in the Democratic primary race but is trailing well behind Biden and Sanders.
Voters on Tuesday are assigning 9 percent of the total pledged delegates to the DNC, meaning 53 percent of the total available delegates will still lie ahead.
To win the Democratic presidential nomination, a candidate must receive support from a majority of all 3,979 pledged delegates on the first ballot of the DNC, which election officials say must be at least 1,991 delegates.
The Republican Party is expected to nominate Trump for a second term during August's national convention in Charlotte, North Carolina.
The 2020 U.S. presidential election will take place on Nov. 3.
