President Donald Trump touted an unlikely new ally Monday in his battle with Democrats over illegal immigration -- the pop star and usually fierce critic Cher.

"I finally agree with @cher!" Trump tweeted after the singer posted her concerns that Los Angeles is in no position to look after poor migrants when it already fails to take care of the homeless.

"I Understand Helping struggling Immigrants, but MY CITY (Los Angeles) ISNT TAKING CARE OF ITS OWN," Cher tweeted on Sunday. "If My State Can't Take Care of Its Own(Many Are VETS)How Can it Take Care Of More."

The post -- in which Cher's eccentric use of punctuation, capitalization and grammar oddly mirrors the president's famously loose writing style -- has been seized upon by Republicans.

They argue, with Trump, that illegal immigration has reached emergency levels requiring drastic action. Democrats say that Trump's policies have created much of the problem and that he exploits tensions for his own political gain.

To push his point, Trump is now threatening to ship huge numbers of migrants across the country into Democrat-led cities and states that have declared themselves "sanctuaries" for migrants, including California.

Critics say this would be unfeasible and illegal without Congress authorizing funding.

Trump repeated the threat on Monday, tweeting: "Those Illegal Immigrants who can no longer be legally held (Congress must fix the laws and loopholes) will be, subject to Homeland Security, given to Sanctuary Cities and States!"