Donald Trump has lamented that New York bombing suspect Ahmad Khan Rahami would receive medical treatment and legal representation after his arrest.
The Afghan-born, 28-year-old was charged with five counts of attempted murder after a police shootout.
The Republican nominee said it was a “sad situation” and underscores the country’s weak national security.
Meanwhile, Democratic rival Hillary Clinton said Mr Trump’s rhetoric only helped terrorist groups.
“The kinds of rhetoric and language that Mr Trump has used is giving aid and comfort to our adversaries,” Mrs Clinton told reporters at a news conference outside New York City.
She added that she was the only candidate equipped with the experience of being “part of the hard decisions to take terrorists off the battlefield”.