[WASHINGTON] White House hopeful Donald Trump, already deserted by some fellow Republicans, came under sharp scrutiny Tuesday over controversial comments that some people interpreted as a threat of violence against his rival Hillary Clinton.
Mr Trump's intended message was not immediately clear, but lawmakers, former national security officials and other critics expressed concern that he had advocated, possibly in jest, that Mrs Clinton or her Supreme Court nominees could be shot.
"Hillary wants to essentially abolish the second Amendment," Mr Trump told a rally in Wilmington, North Carolina, referring to the US Constitution's clause that enshrines the right to bear arms.
"If she gets to pick her judges, nothing you can do, folks," Mr Trump said.
"Although the Second Amendment people - maybe there is, I don't know."
Mr Trump earlier appeared more focused on delivering his typical campaign stump speech about Mrs Clinton, telling supporters she would represent four more years of President Barack Obama, "but maybe worse", and sparring with her over policy.
"I gave a massive tax decrease yesterday," Mr Trump said, referring to economic plans he unveiled Monday.
"Clinton, she's going to double up your taxes."
But then Mr Trump drew attention away from his message with his "Second Amendment" remarks.
It was the latest in a long string of Mr Trump trip-ups - including his clash with the parents of a Muslim American soldier killed in action - that have marred his campaign since he officially won the nomination last month, and prompted several Republicans to reject his candidacy.
Mrs Clinton's campaign decried Mr Trump's "dangerous" language and demanded in a statement that presidential hopefuls "not suggest violence in any way."
Mr Trump's team fired back to say the 70-year-old Manhattan billionaire simply meant that gun rights advocates were a powerful voting force.
"It's called the power of unification - 2nd Amendment people have amazing spirit and are tremendously unified, which gives them great political power," senior Trump communications advisor Jason Miller said.
The National Rifle Association, the nation's largest pro-gun lobby, weighed in, putting forth that Mr Trump was correct in saying it would be hard to protect the Second Amendment if Mrs Clinton appoints new justices.
"But there IS something we will do on #ElectionDay: Show up and vote for the #2A!" the group posted on Twitter.
Mr Trump's "Second Amendment" remarks were not Tuesday's only campaign trail scandal.
Mrs Clinton faced questions after the father of the gunman who killed 49 people at a gay nightclub in Orlando, Florida was spotted at her rally Monday night in nearby Kissimmee.
Seddique Mateen, an immigrant from Afghanistan, was caught on camera seated in the audience behind Mrs Clinton during her campaign appearance at an open rally some 23 miles (37 kilometres) south of Orlando.
"This individual wasn't invited as a guest, and the campaign was unaware of his attendance until after the event," the Clinton campaign said in an email to reporters.
Mr Trump is struggling to transition from his strong grassroots primary effort to a more mature head-to-head battle with Mrs Clinton.
He suffers from sinking poll numbers, including a Quinnipiac University survey released Tuesday that shows him trailing Mrs Clinton in crucial battleground states Ohio and Pennsylvania, and virtually tied in Florida.
Democratic lawmakers expressed shock about Mr Trump's comments.
"In this clip, Trump's either calling for an armed revolt or the assassination of his opponent. Despicable," congressman David Cicilline posted on Twitter along with footage of Mr Trump's remarks.
The Secret Service - which is tasked with protecting both Mr Trump and Mrs Clinton - told US media it was "aware" of the comments, but did not say whether they merited an investigation, which some Democratic lawmakers have said is necessary.
"We must take people at their word. @SecretService must investigate #TrumpThreat," House Democrat Eric Swalwell said on Twitter.
Mr Trump's repeated stumbles and divisive rhetoric have angered Republican Party grandees as well.
Former CIA director Michael Hayden blasted the "Second Amendment" comments as "very arresting."
"It suggests either a very bad-taste reference to political assassination and an attempt at humour, or an incredible insensitivity," he told CNN.
Mr Hayden was among 50 former senior Republican national security officials who warned in an open letter Monday that if Mr Trump were elected he would be "the most reckless president in American history."
The group's comments drew a sharp reply from Mr Trump, who painted them as "nothing more than the failed Washington elite looking to hold onto their power" and saying they should be "held accountable" for making the world less safe.
Influential Republican US Senator Susan Collins piled on, saying the nominee was "unworthy" of America's highest elective office and would not receive her support.
"I have become increasingly dismayed by his constant stream of cruel comments and his inability to admit error or apologise," Ms Collins wrote in a Washington Post op-ed.
She portrayed Mr Trump as a candidate "who will slash and burn and trample anything and anyone he perceives as being in his way or an easy scapegoat."
Retired four-star general Barry McCaffrey also spoke out against Mr Trump, declaring him unfit for the Oval Office and saying it was "remarkable how little he knows" about national security.