Vermont Senator Bernie Sanders has become the Democratic primary’s frontrunner in the key caucus states of Iowa and New Hampshire, according to a CBS News poll, conducted with YouGov.

He has the vote of 43% of likely Democratic caucus voters in Iowa, whereas Hillary Clinton has 33%. The poll of 1670 people has a margin of error of +/- 6.6%.

Among 1350 voters in New Hampshire, Sanders lead widens to 52% versus Clinton’s 30%, with a margin of error of +/- 7.4%.

Clinton comfortably leads Sanders among 1840 registered voters in South Carolina, with 46% of voters preferring her over Sanders’s 23%. The poll there had a margin of error of +/- 6.8%.

In all three states, Vice President Joe Biden polled in third despite not officially tossing his name in the ring.

One place where Sanders is seriously beating Clinton is in overall voter excitement. According to the poll, 78% of Sanders voters expressed “enthusiastic support,” for the candidate compared to 39% of Clinton backers.

Sanders supporters said they were concerned about income inequality, which he has made a cornerstone of his campaign. Both Clinton and Sanders supporters believe the two candidates are interested in middle class issues, but voters overwhelmingly believe Sanders is more invested in policies addressing those concerns than Clinton, with nearly half saying so in New Hampshire and 37% agreeing in Iowa.

Also noteworthy is Sanders’s strong support—70%—among independents, a group that is particularly prevalent in New Hampshire.

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Write to Tanya Basu at tanya.basu@time.com.