The online poll shows Clinton with 50.45 to Trump's 44.65 percent.
Sunday's data reflect a 2.2-percentage point combined shift toward Clinton and away from Trump compared to data collected a day earlier. Over the course of seven days, the full sample size for the poll, Clinton added 1.3 percentage points to her total, while Trump remained nearly flat, adding 0.4 percent. The percentage of "others" in the poll, defined as respondents who declined to pick either candidate, dropped by 1.7 percentage points to 4.9 percent.
The most recent sampling is the third time Clinton has surpassed the 50 percent threshold and marks her highest point in the 2016 UPI/CVoter poll.
The UPI/CVoter online tracking poll surveys about 200 people each day, leading to a sample size of roughly 1,400 people during any seven-day span.
Because the poll is conducted online and individuals self-select to participate, a margin of error cannot be calculated. The poll has a credibility interval of 3 percentage points. This seven-day span includes data collected from Aug. 7 through Sunday, when 1,391 respondents were surveyed. Of them, 975 identified themselves as likely voters.