Sen. Ed Markey did not mince words when describing his feelings about President Donald Trump’s racist tweet this week telling four congresswomen — including Massachusetts Rep. Ayanna Pressley — to "go back" to their countries, despite the fact that all are American citizens and three of the four women were born in the U.S.

Markey said that the president’s tweet is part of his broader campaign strategy to stoke racial tensions in order to bring more white conservative voters to the polls in 2020.

“That’s why his tweets are racist. That’s why his words are racist. That’s why his border strategy is racist,” Markey said during an interview with Boston Public Radio on Wednesday. “It’s an agenda of hate and division, and it’s all meant towards getting him re-elected. Plain and simple,” Markey said.

Markey, who just returned from a trip to the southern border, also criticized the Trump administration’s treatment of immigrants in migrant detention camps. He said detainees were treated inhumanely and were denied basic human services, such as access to showers.

It was “like a prison, but worse in many ways, because they’re not given the sanitary tools [or proper] living standards,” Markey said. “A federal or district court judge, if this was up in Boston, would just come in and just say, ‘Shut this facility down until you can provide humane conditions for people.”

Trump’s latest round of digital sparring has reignited the debate among Democrats over whether to impeach Trump. Some, like Massachusetts Reps. Richard Neal, Stephen Lynch, and Bill Keating say they still need more information before moving forward with impeachment proceedings. Others in the state's congressional delegation, including Sen. Elizabeth Warren and Reps. Ayanna Pressley and Joe Kennedy, say that the president’s actions merit impeachment proceedings.

Markey is somewhere in the middle. He told Boston Public Radio that upon reading special counsel Robert Mueller’s report, he became convinced that the president has committed impeachable offenses, but he also emphasized the importance of building a proper case and not moving too quickly.

“What I read in the Mueller Report contained impeachable offenses,” Markey said. “I do think we’re on the pathway towards an impeachment process. I think all of the evidence that was in the Mueller Report was devastating. So, from my perspective ... every day, Donald Trump brings us closer to impeachment.”