WASHINGTON -- Republican Donald Trump has a message to his fellow Republicans: I'm happy to go it alone.

The GOP candidate told a rally crowd Wednesday afternoon in Atlanta that Republicans can "either stick together or let me just do it by myself."

And he predicted that he can do it "very nicely" alone.

Trump has faced growing backlash from many in his party over various proposals, including his call to temporarily bar foreign Muslims from entering the country.

But Trump brushed off that criticism, insisting his approach will win in November.

He said, "I think you're going to have a very good result. I think we'll be very happy. I'll run as a Republican."

Democrat Hillary Clinton rebuked Trump for proposing national-security ideas that she argued would put the U.S. in greater danger and inspire more terrorist attacks.

The criticism comes as Trump is under fire for offering what Democrats and Republicans have called an off-key response to a mass shooting at a nightclub in Orlando, Fla.

Trump spent the first days after the massacre hinting that President Barack Obama was sympathizing with or even supporting terrorists. The businessman said he was repeating what "many people" believe.

By Wednesday, Trump abandoned the innuendo and embraced a more pointed accusation against Obama.

"Media fell all over themselves criticizing what Donald Trump 'may have insinuated about POTUS.' But he's right," Trump posted on Twitter. The message included a link to a story by Breitbart News, a news and opinion website, that said it had proof the Obama administration backed a terror group in the Middle East.

Trump spokesman Hope Hicks said the candidate was re-tweeting a message from another Twitter user. Still, it was an effort by the GOP's White House pick to explicitly link the sitting Democratic president with those seeking to harm Americans, just days after 49 people were killed and dozens more wounded in Florida.

"Trump's comments regarding the president crossed every line," John Weaver, the senior strategist for Ohio Gov. John Kasich's suspended Republican presidential campaign, wrote on Twitter. He cast Trump as a "peddler of lies, fantasies and half-baked conspiracy theories."

For years, Trump has been the most high-profile proponent of the "birther" movement that falsely claims Obama is a Muslim who was born outside the United States. Obama was born in Hawaii and is a Christian.

In a statement Tuesday, Trump said Obama "continues to prioritize our enemy over our allies, and for that matter, the American people."

During a rally Tuesday night in North Carolina, Trump also suggested that soldiers stole U.S. money from the Iraqi government.

The comments refer to the $12 billion to $14 billion in cash, largely drawn from Iraqi government accounts in the United States, that was flown to Baghdad with the intent that the money be used to introduce liquidity into the area's economy. An investigation from the special inspector general for Iraq reconstruction found that a large part of the money had disappeared.

"How about bringing baskets of money, millions and millions of dollars, and handing it out," Trump said Tuesday night. "I want to know: Who were the soldiers that had that job? Because I think they're living very well right now, whoever they may be."

Trump's use of the word "soldiers" immediately prompted questions about the people to whom he was referring.

Ben Kesling, a reporter for The Wall Street Journal and a veteran of the Marines, interpreted it to be U.S. soldiers. He tweeted: "A presidential candidate just accused me and thousands of other troops of embezzlement while in a combat zone."

Hicks told NBC's Alexandra Jaffe that Trump wasn't disparaging U.S. troops but was instead referring to "Iraqi soldiers."

Clinton's criticism

Clinton quickly challenged Republicans to either "stand up to their presumptive nominee" or "stand by his accusation about our president."

"His comments have become even more inflammatory in recent days," Clinton said after talking about how Trump wanted to halt Muslim immigrants from entering the country. "This approach is not just wrong; it is dangerous."

During a discussion at the Virginia Air and Space Center in Hampton, the Democrats' presumptive presidential nominee argued that such notions were nonsense.

"A ban on Muslims would not have stopped this attack," Clinton said. The gunman, Omar Mateen, was a U.S. citizen born in New York. "Neither would a wall. I don't know how one builds a wall to keep the Internet out."

She said, "Not one of Donald Trump's reckless ideas would have saved a single life in Orlando."

The former secretary of state also criticized Trump over his fixation with the phrase "radical Islam," suggesting he lacked the temperament to lead the country.

"After all the Twitter rants and conspiracy theories you've been hearing recently, it's time for substantive discussions about how we protect our country," Clinton said.

Clinton spent more than an hour Wednesday discussing national security with military members and veterans and taking notes.

Clinton also called for new approaches to stopping lone-wolf terrorists and said people on terrorist watch lists should not be able to buy guns.

The National Rifle Association said Wednesday that it is willing to meet Trump over gun rights for people who are placed on terror watch lists by the government.

Trump said in November he would "absolutely" support blocking terror suspects on a watch list from buying a gun.

On Wednesday, he tweeted, "I will be meeting with the NRA, who has endorsed me, about not allowing people on the terrorist watch list, or the no fly list, to buy guns." He accepted the gun-rights group's endorsement in May.

The NRA, in the same statement, made the case against banning people on the watch list, saying the sale should be "delayed while the investigation is ongoing."

Trump on Obama

Trump's suggestions about Obama come as the president takes a more active role in the White House race. In a speech Tuesday, Obama said Trump was a "dangerous" threat to national security and was putting the United States' religious freedoms at risk by calling for a temporary ban on foreign-born Muslims entering the U.S.

Trump has offered no verifiable information to back up his assertions regarding Obama. His theory was not supported by the document cited in the report he linked to Wednesday -- a secret 2012 Defense Intelligence Agency analysis. The Breitbart story, citing that document, suggested that the United States was in league with al-Qaida in Iraq, the precursor to the Islamic State.

The document states generally what was widely known at the time -- that "the West, Persian Gulf countries and Turkey support the opposition" to the government of Syrian President Bashar Assad.

The U.S. backs several anti-Assad rebel groups but does not include al-Qaida in any negotiations or material or financial support, even as it fights Assad's government. Whether the U.S. cooperated with figures from that group is not addressed in the document.

Trump did not mention the report or his broader accusations during his rally Wednesday in Atlanta. But some of those in the crowd said they were on board with the candidate's assertions.

"I think he's dead on the money," said Brad Butler, a 45-year-old Trump supporter from Dallas, Ga. "So this is Islamic terror and this is his religion. Why would he [Obama] be mad at it?"

Diane Gurganus, 70, from Jefferson, Ga., said she, too, believed that Obama was a Muslim whose religious beliefs were affecting the way he has responded to Islamic State militants and the Orlando attacks.

"It's like his agenda is to destroy America in everything he's done," she said.

But more Republican leaders were coming out against Trump's agenda.

Maryland Gov. Larry Hogan said Wednesday that he does not plan to vote for Trump in November.

Although the first-term Republican has said he does not support Trump, he had never before stated whether he would vote for him in the general election.

During a visit to Prince George's County, Md., on Wednesday, Hogan said he is "not pleased with the candidates in either party. ... I don't think either party has put up its best candidate."

Asked whether he would cast a ballot for Trump, he said, "No, I don't plan to."

He added: "I guess when I get behind the curtain I'll have to figure it out. Maybe write someone in. I'm not sure."

The governor last year endorsed GOP contender Chris Christie, the governor of New Jersey. After Christie left the race and endorsed Trump, Hogan pronounced himself "disgusted with national politics" and said he would not pick another candidate to publicly support.

Clinton, meanwhile, picked up a new endorsement, from MoveOn.org, a group that had backed Sen. Bernie Sanders of Vermont during the Democratic primary.

In a statement Wednesday, MoveOn.org applauded Clinton for her "glass-ceiling-shattering campaign" and urged Democrats to adopt liberal policies at their July convention in Philadelphia.

MoveOn also called for the party to alter its nominating process, something Sanders had espoused during the campaign.

"The best way to defeat Donald Trump and those who support and enable his toxic and hateful campaign is for the Democratic Party to welcome Bernie Sanders' supporters and unite behind a bold progressive agenda for the future," the statement said.

Information for this article was contributed by Julie Pace, Jill Colvin, Erica Werner and Eileen Sullivan by The Associated Press; by Alan Rappeport of The New York Times; by Ovetta Wiggins and Philip Bump of The Washington Post; by Sahil Kapur and Ben Brody of Bloomberg News; and by Kurtis Lee of the Los Angeles Times.

A Section on 06/16/2016