BRIDGEWATER, N.J. — With prominent Republicans openly questioning his competence and moral leadership, President Donald Trump on Thursday burrowed deeper into the racially charged debate over Confederate memorials and lashed out at members of his own party in the latest controversy to engulf his presidency.

Out of sight, but still online, Trump tweeted his defense of monuments to Confederate icons — bemoaning rising efforts to remove them as an attack on America’s “history and culture.”

And he berated his critics who, with increasingly sharper language, have denounced his initially slow and then ultimately combative comments on the racial violence at a white supremacist rally in Charlottesville, Va.

Trump was much quicker Thursday to condemn violence in Barcelona, where more than a dozen people were killed when a van veered onto a sidewalk and sped down a busy pedestrian zone in what authorities called a terror attack.

He then added to his expression of support a tweet reviving a debunked legend about a U.S. general subduing Muslim rebels a century ago in the Philippines by shooting them with bullets dipped in pig blood.

“Study what General Pershing of the United States did to terrorists when caught. There was no more Radical Islamic Terror for 35 years!” Trump wrote.

Trump’s unpredictable, defiant and, critics claim, racially provocative behavior has clearly begun to wear on his Republican allies.

Tennessee Sen. Bob Corker, whom Trump considered for a Cabinet post, said “the president has not yet been able to demonstrate the stability nor some of the competence that he needs to” in dealing with crises.

Sen. Dan Sullivan of Alaska tweeted, “Anything less than complete & unambiguous condemnation of white supremacists, neo-Nazis and the KKK by the (at)POTUS is unacceptable. Period.”

Sen. Tim Scott of South Carolina said Trump’s “moral authority is compromised.”