In his speech, Mr. Trump continued his attack on Mrs. Clinton, accusing her of secretly hating President Obama.

“Remember, Hillary Clinton used to hate Obama,” Mr. Trump said. “She used to hate him. The old Clinton hated him.”

He mocked Mrs. Clinton and her husband, saying they bowed to the president’s whims: “Yes, sir, Mr. President, sir. What would you like? What would you like me to say, sir?” The crowd roared.

He argued that Mrs. Clinton was supportive of Mr. Obama only because of the investigation into her private email server.

“Anything Obama wants, she’s going forward with,” Mr. Trump said. “Because you know why? She doesn’t want to go to jail. That’s why.”

That line of attack closely aligns with the writing of Ed Klein, the conservative author whose books on Mrs. Clinton and Mr. Obama have been dismissed by critics as including fabricated accounts of events. Mr. Trump recently met with Mr. Klein.