Republican US Presidential nominee Donald Trump attends a campaign event at the Ocean Center in Daytona Beach, Florida August 3, 2016. [Photo/Agencies]

WASHINGTON/JACKSONVILLE, Fla.  - Donald Trump's White House campaign was in turmoil on Wednesday after he angered senior Republican Party leaders by criticizing a dead soldier's family and refusing to back the re-election campaign of House of Representatives Speaker Paul Ryan.

On Tuesday, Trump denied support to both Ryan and Senator John McCain in their coming primary contests, hitting back at critics in the Republican leadership who have taken him to task for his insistent public dispute with the parents of the soldier, a Muslim US Army captain killed in the Iraq war.

Republican National Committee Chairman Reince Priebus was furious over the failure to endorse Ryan, who is the most senior elected Republican, and over Trump's feud with the Khan family, two Republican sources said.

"He feels like a fool," a Republican source familiar with the situation said of Priebus.

The RNC did not respond to a request for comment about Priebus.

Another Republican source said Trump's family members, who have played an influential role in his campaign, were aware that an intervention was needed to get Trump back on track. One idea being floated was to have a senior adviser travel with Trump to help him stay on message.

More than any other major figure in the Republican establishment, Priebus worked to bring Trump into the party's fold despite the New York businessman's status as an outsider. Trump, who had never previously run for public office, beat 16 rivals to become the Republican presidential nominee for the Nov 8 election.

Ahead of last month's Republican Party Convention, the RNC chairman sought to rally the fractured party behind Trump. Priebus feels burned by Trump's string of self-inflicted wounds and his refusal to observe basic decorum by giving Ryan his support.

But in what appeared to be an effort to soothe ruffled feelings, Trump's vice presidential running mate, Mike Pence, said on Wednesday he endorsed Ryan as "a strong conservative leader" and was doing so with Trump's blessing.

The Indiana governor told Fox News that it takes time to build relationships in politics and that was exactly what Trump and Ryan were doing.

Trump has had a running dispute with the parents of Army Captain Humayun Khan since they took the stage at last week's Democratic National Convention. Khizr Khan, with his wife, Ghazala, standing by his side, cited the sacrifice of their son, who was killed by a car bomb in 2004, and criticized Trump's proposal to combat terrorism by temporarily banning Muslims from entering the United States.

Many Republican leaders, including Ryan and McCain, have criticized Trump's subsequent attacks on the parents. Even longtime ally Chris Christie, the Republican New Jersey governor, said it was inappropriate to attack the Khans.

Trump's feud with the Khans was the final straw for Republican congressman Adam Kinzinger, a former Air Force pilot and Iraq war veteran. Kinzinger, who had held off supporting Trump, told CNN on Wednesday: "I just don't see how I get to Donald Trump anymore."

Trump, who made his comments about Ryan and McCain in an interview with The Washington Post, shrugged off the backlash.

"There is great unity in my campaign, perhaps greater than ever before. I want to thank everyone for your tremendous support. Beat Crooked H!" he wrote on Twitter early on Wednesday, referring to his Democratic rival, Hillary Clinton.

Campaign manager Paul Manafort told Fox News the campaign was moving in a positive direction, with Trump himself in control. "The campaign is in very good shape. We are organized. We are moving forward," Manafort said.

In Daytona, Florida, Trump said the news media's coverage of him was dishonest.

"We're doing quite well despite the fact that we get a totally false narrative," he told supporters at a rally.

At another campaign event in Florida, in Jacksonville, Trump pointed out a group of families, known as Gold Star families, who have lost loved ones in war, calling them "incredible people." He didn't mention the spat with the Khans.