Republican Donald Trump insisted Wednesday that his presidential campaign is unified, even as he faces open revolt from some in his party amid one of the most disruptive controversies of his unruly White House run."There is great unity in my campaign, perhaps greater than ever before. I want to thank everyone for your tremendous support. Beat Crooked H!" the Republican nominee wrote on Twitter early on Wednesday, referring to Democratic rival Hillary Clinton.The message belied the chaos that has erupted in the Republican Party after Trump engaged for days in a public dispute with Khizr and Ghazala Khan, the parents of a Muslim American soldier who died in Iraq.The uproar has led many Republicans to distance themselves from Trump and voice support for the Khan family. Several media outlets reported Wednesday that the campaign is in disarray and that Trump had rejected advice from his staff to drop the battle with the Khans.ABC News reported Wednesday that Republican National Committee Chairman Reince Priebus is furious about the dispute with the Khans and has spoken with Trump repeatedly, asking him to change course.According to the same report, senior officials are looking into how to replace Trump on the Republican ticket for the November 8 election. The Trump campaign had no immediate comment.Late on Tuesday, Meg Whitman, a prominent Republican fundraiser and chief executive of Hewlett Packard Co, endorsed Clinton's White House bid, calling Trump an "authoritarian character" and a threat to democracy.In an interview with The New York Times, Whitman said it was time to "put country first before party."Trump has verbally sparred with the Khans since they took the stage at last week's Democratic National Convention in Philadelphia to cite their son's sacrifice and to criticize Trump's proposal to combat terrorism by temporarily banning Muslims from entering the US.Many Republican leaders, including House of Representatives Speaker Paul Ryan and Senator John McCain, have criticized Trump's attacks on the Khans, whose son Army Captain Humayun Khan received the Bronze Star Medal after he died in combat in Iraq in 2004.Trump struck back in an interview with The Washington Post on Tuesday, refusing to support both Ryan and McCain in their re-election bids.Even Trump's longtime ally New Jersey Governor Chris Christie said Tuesday that it was inappropriate to criticize the Khan family.Richard Hanna, a representative for New York, became the first Republican in Congress to endorse Clinton, although several other Republicans in Congress have said they will not support Trump.