Delaware Gov. John Carney tweeted Tuesday that he would refuse to send National Guard troops to the nation's Southwest border until the Trump administration ends its policy of separating immigrant families from children.

Carney, a Democrat, called the policy "inhumane" and said Congress and President Trump need to "fix the mess that our immigration system has become."

In Massachusetts, Republican Gov. Charlie Baker has also refused to send troops to the border, citing the "cruel and inhumane" separation of families. Another GOP governor, Larry Hogan of Maryland, refused as well, tweeting: "Immigration enforcement efforts should focus on criminals, not separating innocent children from their families."

New Jersey Gov. Murphy vowed to prevent "state resources from being used to help federal authorities separate families," while Pennsylvania Gov. Wolf criticized the policy. Both are Democrats.

Later Tuesday, Wolf expanded on his earlier tweet.

More than 2,000 minors have been separated from adults in the six weeks following Attorney General Jeff Sessions' announcement of the zero-tolerance approach to illegal border crossings. Some children have been kept in large cages, while others have been placed in a tent city.

Health experts have said children can suffer lifelong physical and psychological challenges when they are forcibly separated from a parent. On Monday, ProPublica released audio of children at a border facility wailing and screaming "Mami" and "Papá."

Trump and other administration officials have falsely — and repeatedly — claimed that Democrats and existing laws are to blame for the separation of families. As the Washington Post reports, that's simply not true:

Immigrant families are being separated at the border not because of Democrats and not because some law forces this result, as Trump insists. They're being separated because the Trump administration, under its zero-tolerance policy, is choosing to prosecute border-crossing adults for any offenses.

The administration could end the policy at any time.

All four living former first ladies have criticized the policy. Laura Bush wrote in The Post: "I live in a border state. I appreciate the need to enforce and protect our international boundaries, but this zero-tolerance policy is cruel. It is immoral. And it breaks my heart."

Two-thirds of the country, 66 percent, opposes Trump's policy, according to a poll from Quinnipiac University. That includes six in 10 men and seven in 10 women.

As is often the case, though, there's a wide split by party. A majority of Republicans approve of the policy, while six in 10 independents and nine in 10 Democrats oppose it.

This article contains information from the Washington Post and the Associated Press.