Donald Trump's presidential campaign has asked GOP lawmakers to back him in his fight against Khzir Khan, the Gold Star father who denounced him at the Democratic National Convention.

"We want to get several member statements out today on this, and would really appreciate your help," Rob Wasinger, Trump's liaison to lawmakers, wrote to GOP aides in a message obtained by Reuters.

Khan accused Trump of "smear[ing] the character of Muslims," being ignorant of the Constitution and invoked his son's death in Iraq before attacking Trump: "You have sacrificed nothing and no one."

The GOP nominee replied by implying that Khan had barred his wife from speaking during the speech. One of his informal advisers followed up with the allegation that Khan is "a Muslim Brotherhood agent helping Hillary [Clinton]," and Trump's immigration hawk allies noted that Khan is an immigration lawyer.

Republican lawmakers haven't followed Trump's lead, however.

"I hope Americans understand that the remarks do not represent the views of our Republican Party, its officers or candidates," Sen. John McCain, R-Ariz., who faces a difficult re-election campaign, said Monday.

"I claim no moral superiority over Donald Trump. I have a long and well-known public and private record for which I will have to answer at the Final Judgment, and I repose my hope in the promise of mercy and the moderation of age. I challenge the nominee to set the example for what our country can and should represent."