WASHINGTON (Reuters) - 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 Senator 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. Trump’s dispute with the Khans has dominated the White House campaign in recent days and underlined the uneasy alliance between many leading Republicans and the party’s freewheeling, unorthodox nominee for the Nov. 8 election. Rob Wasinger, a onetime congressional candidate who has been working for the Trump camp on congressional outreach, sent an email to senior Senate aides saying, “We want to get several member statements out today on this, and would really appreciate your help.” A similar appeal was made to Republicans in the House of Representatives, according to a senior aide. Attached to the appeal were talking points lawmakers could use to try to tamp down the controversy growing since last week’s appearance at the Democratic convention by the Khans, the parents of U.S. Army Captain Humayun Khan, who was killed by a bomb in Iraq 12 years ago. Hope Hicks, a spokeswoman for Trump, said that the campaign was grateful to have support in Congress and that Republicans are working to keep Democratic nominee Hillary Clinton from winning the presidency. Wasinger refused to comment when contacted by telephone. The appeal did not generate any help for Trump. A senior Senate Republican aide, who asked not to be identified, said Republican senators were pleased with Senate Majority Leader Mitch McConnell’s statement on Sunday calling Captain Khan “an American hero” and noting “a travel ban on all members of a religion is simply contrary to American values.” At the same time, the aide said the controversy would probably not cause Republican senators to withdraw their endorsements of Trump. In a convention speech delivered with his wife at his side, Khizr Khan showcased his son’s military service and criticized Trump’s call for a temporary ban on Muslims from entering the United States, holding up a copy of the U.S. Constitution and suggesting Trump read it. Since then, Trump has complained he was “viciously” attacked by the couple and suggested Ghazala Khan might not have been “allowed” to speak, implying her silence reflected restrictions placed on women by some traditional Muslims.  McCain, the 2008 Republican presidential candidate and current chairman of the Senate Armed Services Committee, issued a lengthy statement sharply criticizing Trump’s comments. “While our party has bestowed upon him the nomination, it is not accompanied by unfettered license to defame those who are the best among us,” said McCain, a prisoner of war for five years during the Vietnam War. His counterpart on the House Armed Services Committee, Representative Mac Thornberry of Texas, echoed McCain, saying in a statement he was “dismayed at the attacks Khizr and Ghazala Khan have endured after they spoke about their son’s service and sacrifice.” The head of the 1.7 million-member Veterans of Foreign Wars also said Trump’s attack on the Khans went too far. Trump and Clinton spoke to the group’s national convention last week. “Election year or not, the VFW will not tolerate anyone berating a Gold Star family member for exercising his or her right of speech or expression,” said Brian Duffy, the national commander of the country’s oldest and largest war veterans organization, referring to families who have lost relatives in wars. President Barack Obama did not mention Trump by name, but said military families who had lost loved ones in service should be honored for their sacrifice. “No one has given more for our freedom and our security than our Gold Star families,” Obama said at the Disabled American Veterans national convention in Atlanta. “Our Gold Star families have made a sacrifice that most of us cannot even begin to imagine. They represent the very best of our country.” In the talking points sent to lawmakers, the Trump campaign said he had been asked about the Khans’ comments during the convention and wished them well. The talking points also noted that Trump “wants to end radical Islamic terror, so that our soldiers like Mr. Khan’s son will be safe.” The list also says Trump had not directly compared his sacrifices to the Khans. Trump said over the weekend he had also made sacrifices in his life by working hard, creating jobs and being successful. The Khans bristled at that suggestion and, in numerous television appearances over the weekend, said Trump was ignorant about Islam and about their family’s sacrifice.   Trump’s off-the-cuff insults and controversial proposals such as the Muslim ban and a plan to keep illegal immigrants out by building a wall along the Mexican border, have made many in the party establishment reluctant backers of his White House bid. On Monday, during a town hall event in Columbus, Ohio, Trump told supporters he thought the November election might be “rigged.” Later that day, he said former Democratic presidential candidate Bernie Sanders “made a deal with the devil” when he agreed to back Clinton. “She’s the devil,” Trump said, referring to Clinton. In his statement, McCain recalled how Humayun Khan died, saying that when a suicide bomber aimed his vehicle toward a building housing hundreds of U.S. soldiers, the captain told his subordinates to stay away, then ran toward it. McCain thanked the Khans for coming to America, saying “your son was the best of America, and the memory of his sacrifice will make us a better nation – and he will never be forgotten.”  In a remarks to television networks on Monday, Khizr Khan said Trump lacked the empathy to be a leader and chided him for throwing the first salvo in their exchange. Trump has tried to shift focus from the Khans. “This story is not about Mr. Khan, who is all over the place doing interviews, but rather RADICAL ISLAMIC TERRORISM and the U.S. Get smart!” Trump said Monday on Twitter. Ghazala Khan wrote an opinion piece in The Washington Post on Sunday saying she had remained silent during her husband’s remarks to cope with making her grief public during the convention. On Sunday, Democratic rival Clinton said Trump had scapegoated the parents. In addition to Senate Majority Leader McConnell, House Speaker Paul Ryan issued a statement supporting the family.  Trump drew similar opprobrium a year ago when he said McCain, who as a naval aviator was shot down and taken prisoner during the Vietnam War, was not a hero because he had been captured. In an open letter, 23 Gold Star families said Trump cheapened their sacrifice and called for an apology. “This goes beyond politics. It is about a sense of decency,” it said. “That kind decency you mock as ‘political correctness.’” 