U.S. Democratic lawmakers on Friday called President Donald Trump's latest anti-immigration initiatives "unacceptable" and warned his administration against misappropriating funding authorized only for humanitarian use.

The criticism came as two congressional delegations toured the U.S.-Mexico border area near McAllen, Texas, as part of efforts to oversee policies banning nearly all asylum-seekers from entry, warehousing detainees in crowded quarters and holding children separately from the adults they traveled with.

Read more:

Trump tweets his way into another firestorm

"The administration has continued to push anti-immigrant policies that have hurt migrants, endangered asylum-seekers and exacerbated the humanitarian crisis," U.S. Representative Kathleen Rice, a Democrat leading a bipartisan House delegation, said in a statement. "This is unacceptable."

While Democrats have denounced Trump for precipitating what they consider a humanitarian crisis, the president's supporters have applauded him for cracking down on illegal immigration along the 2,000-mile (3,000-km) border.

Immigration, one of Trump's signature issues in the 2016 presidential campaign, is already shaping up as a central issue in November 2020.

Senate Democrats warned Trump against misusing any of the 4.5 billion U.S. dollars in humanitarian aid that congress approved last month, saying in a letter that lawmakers would "scrutinize" how the funds were spent.

The supplemental spending was meant to "alleviate and improve the inhumane conditions faced by children and families seeking refuge at the southern border," the letter said.

In the past, Democrats have criticized Trump for attempting to use funds set aside for the Department of Defense for border wall construction.

A Department of Homeland Security spokeswoman said on Friday it would expand a program forcing migrants to await their U.S. hearings on the south side of the border. The government will add Brownsville, Texas, as a fifth border city for processing applications of migrants who must wait for a decision in Mexico.

The Migrant Protection Protocols, or MPP, is one of the few immigration programs initiated by the Trump administration that courts have allowed to proceed while a lawsuit to stop the program is under consideration. Federal judges have blocked other measures to limit asylum applicants at the U.S.-Mexico border until legal challenges go to trial.

The MPP is unusual in that the U.S. government has secured the cooperation of the Mexican government. Under pressure from Trump, Mexico agreed to take in migrants, mostly from Central America, returned to the south side of the border while they await their U.S. court hearings.

The program began in January in San Diego, and has been expanded to Calexico, California, and to El Paso, Laredo and now Brownsville in Texas.

Trump's tough stance on immigration has been criticized for a long time. He has come under intense fire after he attacked four first-term Democratic congresswomen known as the "Squad" by calling them to "go back" to their countries of origin if they are not happy in the United States.

Former first lady Michelle Obama Friday rebuked Trump's comments, saying "there's a place for all of us." "What truly makes our country great is its diversity... Whether we are born here or seek refuge here, there's a place for all of us," Obama tweeted, without mentioning Trump. "We must remember it's not my America or your America. It's our America."

(With input from Reuters, AFP.)

(Cover: An immigrant family walks along the border fence after crossing illegally into the United States to turn themselves in to U.S. Customs and Border Protection officials to request for asylum in El Paso, Texas, U.S., July 9, 2019. /VCG Photo)