U.S. Republican Donald Trump's presidential campaign appealed to Capitol Hill for support on Monday as his attacks on the Muslim parents of a decorated American soldier killed in Iraq drew sharp rebukes from fellow party members.

Trump's criticism of Khizr Khan and Ghazala Khan, who took the stage at last week's Democratic convention, sparked growing concern and dismay from Republican lawmakers responding to the latest Trump outburst to blindside his party colleagues.

Republican Sen. John McCain, a former prisoner of war and the most prominent veteran in Congress, along with the commander of the Veterans of Foreign Wars, joined the chorus of condemnation, reflecting the highly regarded place the military and its veterans hold with many in the United States.