Democratic presidential candidate Julián Castro slammed President Trump's planned July 4th celebration, calling it a "waste of money" meant to boost the president's ego. On Thursday, U.S. Army tanks will be in the city, and Mr. Trump will deliver a July 4th speech at the Lincoln Memorial.

In an interview with "CBS This Morning," Castro chastised Mr. Trump's administration for reportedly diverting $2.5 million from the National Park Service to the celebration and focusing on a military procession instead of improving conditions for American veterans.

"Instead of addressing something like veteran homelessness, he's spending it on boosting his ego with a parade that's fundamentally about him," said Castro, who served as secretary of Housing and Urban Development in the Obama administration.

Mr. Trump tweeted Wednesday morning that "our July 4th Salute to America at the Lincoln Memorial is looking to be really big" and will be "the show of a lifetime."

"What a waste of money," Castro said about the president's planned "Salute to America."

Castro also criticized Mr. Trump for the terrible conditions at many migrant detention centers at the border. The Department of Homeland Security's (DHS) internal watchdog found squalid conditions in several detention centers for migrant families and children in Texas. The watchdog found "serious" overcrowding, minors going without hot meals for days and detainees begging not to be returned to their cells, according to a new report released Tuesday.

"This president has used migrants as kind of a political piñata to get elected," Castro said, accusing the president of "cruelty" in his immigration policies.

Castro also further discussed his proposal to decriminalize illegal immigration and instead use a civil process to prosecute undocumented migrants instead of a criminal process.

"We have a border that is being secured and we can maintain security," he said in response to criticism that decriminalization could lead to an influx of illegal migration.

Castro has also proposed a "21st century Marshall Plan" to improve conditions in Central America, where political turmoil is leading many migrants to flee to the U.S.

"They're coming because they can't find safety and opportunity in their home country," Castro said about these migrants.