Hillary Clinton's popularity among the coveted college demographic is slipping away quickly, according to a poll released Tuesday afternoon by the California-based online textbook company Chegg.

In the nationwide survey of college students enrolled at two or four-year universities, just 18 percent selected the former secretary of state as the Democratic candidate who holds their support. When the survey was first commissioned in mid-June, Clinton led Vermont Sen. Bernie Sanders and Vice President Joe Biden by nearly 20 points each, with 40 percent support.

While Clinton, the long-presumed Democratic nominee, has fallen 22 points in less than three months, the percentage of college students backing Sanders as their Democratic candidate of choice has climbed nearly 34 percent, putting the self-described socialist at 59 percent support among the undergraduate respondents.

Asked who their second choice would be to secure the Democratic nomination, an equal number of college students, 29 percent, selected both Clinton and Biden.

Clinton also received the highest unfavorable rating in the Democratic field with 47 percent of college students holding negative views of the former first lady, earning her a net-negative score of 47-42 percent. Meanwhile, Sanders had the highest favorability rating of any candidate, Democratic or Republican, with 62 percent of students viewing him positively.

When it comes to the type of candidate college voters wish to see occupying the Oval Office in 2016, 53 percent of respondents said they would prefer an "outsider [or] newcomer," while less than a quarter said they would like to see a Washington insider as the next commander in chief.

Additionally, candidates touting "free college" or "debt-free college" as a way to make inroads with the traditionally left-leaning demographic are less likely to receive students' support when compared with candidates who've offered practical solutions toward tackling the rising student debt bubble and improving income repayment plans for student loans.

Fifty percent of respondents said solving the latter was the higher education issue candidates should be focused on while just 12 percent said providing free community college should be the top priority.

Chegg's ongoing national survey began in June and was conducted online through Sept. 11 with a combined sample size of more than 2,500 students. The polling data's margin of error is 5 percent.