President Donald Trump is criticizing polls that seem to indicate that a majority of American voters want him impeached and removed from office.

The latest poll the president had an issue with was a Fox News poll that stated that 51% of voters were in favor of impeachment. President Trump said that Fox News’s pollsters, “suck.”

But Monmouth University Polling Institute Director Patrick Murray says that across the board, polls seem to indicate that support for the impeachment process is on the rise. President Trump once called Murray “highly respected.”

The latest call for impeachment comes after a scandal over whether the president dangled military aid and a White House visit in exchange for Ukraine's leader ordering an investigation into former Vice President Joe Biden's family.

Murray says that support for impeachment “has gone up. It has gone up among every pollster, no matter how you ask the question. It's gone up probably a good eight points.” This includes the Fox News polls, which Murray says are “solid” polls.

“If he's not seen as universally popular among his base, that's problematic so the fact that Fox does not skew its polls is problematic for the president,” Murray says.

On Monday, Trump quoted on Twitter a news story criticizing Montgomery-based Braun research. The firm makes the phone calls for Fox News' polls and for Murray's.

“They are never responsible for how I sample, how I weigh, what my analysis is,” Murray says. “They’re contractors. I tell them the job to do and what to do.”

A representative from Braun Research could not be reached for comment.

Murray says the president still has strong support among voters who identify as Republicans. But –

“Fifteen, 16% of Republicans, people who are calling themselves Republicans, say that it’s time to move with impeachment on Donald Trump,” he says.

Murray has compared support for impeaching and removing Trump - 44% 2 weeks ago - to support for removing President Richard Nixon, which was at 46% when the House launched his formal impeachment inquiry.

Trump's job approval rating has been relatively steady in the low 40 percentage points, while Nixon's fell from 44% to 25% in 10 months, just before he resigned in 1974.