A new poll shows Brazilian President Dilma Rousseff's popularity has suffered another hit after massive protests swept Brazil last month.

The National Transport Confederation poll released Tuesday shows Rousseff's approval rating plummeted from 73.7 percent in June to 49.3 percent in July.

The poll by the group representing private transportation businesses surveyed 2,002 people on July 7 and 10 and has a margin of error of 2.2 percentage points.

It is the second poll that shows a sharp drop in Rousseff's popularity since the protests began.

Last month, the Datafolha polling institute said 30 percent of respondents rated Rousseff's government as "great/good" compared to 57 percent who gave it that rating before the demonstrations began.