While new 2020 polling may show Sen. Bernie Sanders (I-Vt.) with a strong double-digit lead among Democratic primary voters, it also suggests that his health could become a big factor against him if he's the party's nominee in the general election.

According to the results of an NBC News/Wall Street Journal poll released Tuesday, the Vermont senator and self-described democratic socialist leads the Democratic primary field with 27% of support among Democratic primary voters, which is 12 points ahead of the second-place candidate, former Vice President Joe Biden.

But the results aren't all rosy for Sanders. The poll also asked an overall sample of registered voters about their thoughts on candidates' qualities in a general election.

That section of the poll shows that a total of 57% of registered voters either "had some reservations" (42%) or were "very uncomfortable" (15%) about a candidate who had a heart attack in the last year.

It also shows that 53% of voters "had some reservations" (39%) or were "very uncomfortable" (14%) about a candidate over the age of 75. Sanders, 78, shares that distinction in the Democratic field with 78-year-old former New York City Mayor Michael Bloomberg and 77-year-old Joe Biden. President Donald Trump is 73 years old.



Sanders was already fielding concerns about his age before he had the heart attack in October, after which his campaign was accused of an "inexcusable three days of silence" for keeping people in the dark about what had happened. Earlier this month, the candidate backtracked on a pre-heart attack pledge he made to release his medical records, saying, "We have released a substantive part, all of our background. We have doctors who have, cardiologists who are confirming that I am in good health."

But the results show that Sanders' socialist views and image could prove to be a bigger stumbling block with voters than questions about his health. Some 67% of voters said that they either "had some reservations" (21%) or were "very uncomfortable" (46%) about a socialist candidate.

Democratic pollster Peter Hart, who helped conduct the survey, told NBC News, "There is one clear and inescapable set of results: Bernie Sanders is the definitive front-runner, and the current numbers do not represent his ceiling, but instead his base with room to grow." Hart also acknowledged that the candidate's "downsides are there" but have "yet to be exploited by his opponents."