Democratic presidential candidate Bernie Sanders has argued that he is more electable than Hillary Clinton against a Republican. The latest polls revealed his claim to be true, at least in the state of New Hampshire.

According to a recently released poll conducted by NBC News and The Wall Street Journal, Clinton leads Sanders by just three percent among potential Iowan voters. In New Hampshire, where the Vermont senator has kept a small lead for the past few months, he's up by four.

"Secretary Clinton and her campaign now know that she is in serious trouble," Sanders said at a rally in Pleasantville on Monday, as per NYTimes. "And, I think a candidate who was originally thought to be the anointed candidate, to be the inevitable candidate, is now locked in a very difficult race here in Iowa and in New Hampshire."

Speaking on ABC's "This Week," Sanders told George Stephanopoulos that if Democrats are concerned about electability, Bernie Sanders is the perfect candidate. He added, "Democrats should be very concerned because we certainly don't want to see some right-wing extremist in the White House."

The 74-year old politician's steady rise has been remarkable, especially for a senator who was reluctant to run in the first place. Some sectors viewed Sanders as a candidate out to make a point, but not to win the 2016 presidential election. Those who hoped Sanders would win believed it would be his sincere and unwavering stance on income inequality that would attract voters.

Sanders, who happens to be the oldest candidate in this year's presidential race, is also winning the support of young voters.

A new poll from USA Today and Rock the Vote showed that 18- to 35-year-olds prefer Sanders over Hillary Clinton, 46 percent to 35 percent.

It's still unclear if the respondents are going to turn out to vote for the Vermont senator, but it's the latest proof that millennials don't mind the prospect of voting for a self-described democratic socialist. It can also be said that Sanders's messages regarding education and the economy have resonated among younger voters.

In December, the Harvard Institute of Politics released a similar poll and found that Sanders had a six percent advantage over Clinton. Only nine percent of millennials said Sanders's penchant for socialism made them less likely to vote for him.

Sanders is mostly popular among young white voters and those enrolled in college. Black and Hispanic young people preferred Clinton.

Clinton, meanwhile, has spent the last couple of days criticizing Sanders for being, in her view, lenient on gun control. She is currently rolling out an endorsement from Transportation Secretary Anthony Foxx and a group of female senators in Iowa.