US Democratic presidential candidate Bernie Sanders laughs as he speaks to his wife Jane (not shown) on the campaign's bus after speaking at a campaign event in Charles City, Iowa January 30, 2016. [Photo/Agencies]

Once being regarded as a long shot, Vermont Senator Bernie Sanders now poses real threat to Hillary Clinton's race to the White House, especially in Iowa and New Hampshire, the two states which hold the first two primary elections.

A native from Brooklyn, New York, Sanders was elected as mayor of Burlington, Vermont and won his Senate election in 2006. If elected, he would be the first Jewish president of the country.

The majority of his support in this election cycle comes from the liberal wing of the Democratic Party, and his rallies can attract thousands of young people to attend.

According to the final poll before the Iowa caucuses by the Des Moines Register/Bloomberg Politics, he is now trailing Clinton in Iowa by three points.