A retired four-star Navy admiral and former advisor to President Barack Obama called on Republicans to "repudiate" Donald Trump over the nominee's ongoing feud with the parents of a slain Army captain.
Adm. John B. Nathman, who retired in 2007, called the Republican businessman "unstable" and said his war of words with Khizr and Ghazala Khan should disqualify him from becoming president.
"As Mr. Khan reminded us, it's time now for American leadership to repudiate Donald Trump," Nathman wrote in a statement reprinted by CBS News. "What is required is not just the recognition of Trump's lack of temperament to serve, but I would add it also takes personal courage to say it out loud."
Nathman is a longtime Democrat and supporter of Democratic causes. Shortly after retiring he co-chaired then-Sen. Obama's presidential campaign in 2008 and delivered a speech at the 2012 Democratic National Convention, when Obama was opposed by former Republican Massachusetts Gov. Mitt Romney.
"Where is the personal courage of national Republican leaders when it comes to telling Americans this man is not fit for the Presidency of the United States?" Nathman wrote. "It's time to stop pretending Trump is in any way an acceptable candidate. His unstable temperament and ignorance make it clear he cannot serve as president."
Trump hasn't responded to Nathman, but tweeted on Aug. 3 disputing reports of internal strife in his campaign.
"There is great unity in my campaign, perhaps greater than ever before," Trump tweeted.