A new Morning Consult poll indicates that Sen. Bernie Sanders, I-Vt., could pose some problems for Hillary Clinton in the New Hampshire Democratic primary.

Among New Hampshire primary voters, 43 percent said they plan to vote for Clinton, while 32 percent said they are eyeing Sanders, the Morning Consult reported, noting that New Hampshire provided Clinton her biggest boost in 2008. Vice President Joe Biden, who hasn't yet indicated that he plans to run, received support from 8 percent of likely Democratic voters.

Sanders, a self-described "Democratic socialist," has been campaigning to Clinton's left with promises of political revolution. The 73-year-old has vowed to rein in Wall Street banks, end perpetual wars, dismantle "disastrous" trade deals like the Trans-Pacific Partnership, provide free college education and create a government-financed jobs program, according to The Associated Press.

It's a slightly different story in the key battleground state of Iowa, where 54 percent of Democratic primary voters said they favored Clinton, 12 percent prefer Sanders, and 9 percent support Biden. In South Carolina, 56 percent said they favored Clinton, 15 percent Biden, and 10 percent Sanders.

Former Maryland Gov. Martin O'Malley, who announced his candidacy at the end of May, took 3 percent in South Carolina, 2 percent in New Hampshire and 1 percent in Iowa.

The survey polled 816 registered voters in New Hampshire, including 279 likely Democratic voters; 905 registered voters in Iowa, including 313 likely Democratic caucus-goers; and 906 registered voters in South Carolina, including 309 likely Democratic primary voters.

The margin of error for each state is 3 percent, while the margin of error for the Democratic samples in all three polls is plus or minus 6 percent.