Thirty-six percent of voters now view special counsel Robert Mueller's investigation in a negative light, according to a Politico-Morning Consult poll released Wednesday.

That's a significant rise from the 23 percent who viewed Mueller's probe negatively in July 2017 and suggests the criticism by the Trump administration and its allies in Congress and the media is eroding public support for the investigation.

More than half of Republican voters - 53 percent - say they view the special counsel unfavorably. That represents a 26-point increase from when the poll first started asking voters about their perceptions of Mueller in July 2017.

The number of Democrats who view Mueller unfavorably has also increased to 24 percent, while 33 percent of independent voters have a negative view of the special counsel.

The Politico-Morning Consult poll found that 40 percent of voters believe that Mueller's probe has been handled unfairly - a 6-point increase from February.

Thirty-eight percent say the investigation is being conducted in a fair manner, according to the survey.

Mueller took over the criminal investigation into Russia's role in the 2016 presidential election in May 2017, and he has so far netted 18 indictments of companies and individuals, including former Trump campaign chairman Paul Manafort.

He has also secured five guilty pleas, including from former national security adviser Michael Flynn, who admitted to lying to FBI agents about his interactions with a Russian ambassador before Trump took office.

Mueller's probe has repeatedly come under attack from Trump and his political allies, who have insisted that the investigation is a "witch hunt" intended to undermine the president's work in office. Mueller is also examining whether Trump sought to obstruct the probe.

According to the Politico-Morning Consult poll, nearly half of voters - 48 percent - believe that Trump has tried to impede the investigation. That's up from 44 percent in February.

But that belief is sharply divided along party lines, with 79 percent of Democrats saying that Trump is trying to obstruct the investigation and 70 percent of Republicans saying he is not.

The poll surveyed 1,994 registered voters from June 7 to 10. It has a margin of error of 2 percentage points.