WASHINGTON -- President Barack Obama on Tuesday labeled Donald Trump "unfit" and "woefully unprepared" to serve in the White House. He challenged Republicans to withdraw their support of their party's presidential nominee, declaring "There has to come a point at which you say, 'enough.'"

Obama questioned whether Trump would "observe basic decency" as president, argued that Trump lacks elementary knowledge about domestic and international affairs, and condemned his disparagement of an American Muslim couple whose son was killed while serving in the U.S. Army in Iraq.

A chorus of Republicans -- including U.S. Sen. Tom Cotton of Arkansas -- has disavowed Trump's criticism of the Muslim GI's parents, Khizr and Ghazala Khan, and Trump's calls to temporarily ban Muslims from coming to the U.S.

But Obama argued that such disavowal isn't enough.

"If you are repeatedly having to say, in very strong terms, that what he has said is unacceptable, why are you still endorsing him?" Obama asked during a White House news conference. "What does this say about your party that this is your standard-bearer?"

Few Republican lawmakers have publicly withdrawn their support of Trump.

But Trump is withholding his support of some top GOP lawmakers, including House Speaker Paul Ryan and Sen. John McCain of Arizona. Trump told The Washington Post that he wasn't "quite there yet" on an endorsement for Ryan's primary campaign.

Trump's refusal to back Ryan exposed anew the deep divisions within the GOP and underscored that the businessman rarely plays by the traditional political playbook. Ryan has been among those urging Republicans to rally around Trump, despite concerns about his candidacy.

Ryan's campaign said: "Neither Speaker Ryan nor anyone on his team has ever asked for Donald Trump's endorsement. And we are confident in a victory next week regardless."

Trump said he refused to endorse McCain, who was a prisoner of war in Vietnam, for not doing enough for veterans.

"I've never been there with John McCain because I've always felt that he should have done a much better job for the vets," Trump told the Post.

Trump also said he dismissed Sen. Kelly Ayotte as a weak and disloyal leader in New Hampshire. She's running for a second Senate term and skipped the Republican National Convention.

"You have a Kelly Ayotte who doesn't want to talk about Trump, but I'm beating her in the polls by a lot," Trump said. "We need loyal people in this country. We need fighters in this country. We don't need weak people."

The primary election for Ryan's House seat in Wisconsin is next week. McCain is in a three-way race ahead of an Aug. 30 primary in Arizona, and Ayotte's primary in New Hampshire is next month.

All three chided Trump for engaging in a flap with the Khans, the parents of U.S. Army Capt. Humayun Khan, who was posthumously awarded a Bronze Star and Purple Heart after his death in 2004 in Iraq.

Khizr Khan, with his wife standing beside him, spoke at last week's Democratic National Convention. Khan criticized Trump's position on Muslims and asked whether the real estate mogul had read the Constitution.

Trump said the grieving father had "no right" to criticize him. He later acknowledged that their son is a hero. Trump also questioned why Ghazala Khan did not speak at the convention, implying that her religion prevented her from doing so, and saying Khizr Khan "viciously attacked" him.

McCain responded to those comments with a lengthy denunciation in which he said Trump does not have "unfettered license to defame those who are the best among us."

Ryan condemned any criticism of Muslim Americans who serve the country. Ayotte declared she was "appalled" by Trump's criticism of the Khans.

Among the other Republicans denouncing Trump's comments was Rep. Mike Coffman, who is running for re-election in a competitive Colorado district and who said he was "deeply offended when Donald Trump fails to honor the sacrifices of all of our brave soldiers who were lost in that war." Sen. Roy Blunt of Missouri said the Khans "deserve to be heard and respected."

Sen. Mark Kirk, who is facing a tough re-election fight in Illinois, rescinded his endorsement of Trump in June after the GOP nominee criticized a U.S.-born judge's Mexican heritage. Others, including Senate Majority Leader Mitch McConnell and Ryan, have broken with the nominee on individual issues but continue to back his candidacy.

Florida's U.S. Sen. Marco Rubio, who has joined with top Republicans in denouncing Trump's criticism of the Khans, said he could not imagine rescinding his endorsement of the Republican presidential nominee.

"That would mean supporting Hillary Clinton, who I would never be able to support," Rubio said Tuesday.

Rubio called Trump's comments on the Khans "unfortunate" and the situation "bad." He said he hoped the campaign and party could emerge from controversy because "that family deserves our respect."

He added, "At the end of the day, despite the fact I disagree with Donald on a number of things, including his statement on this, I disagree with her on everything."

Obama, at the White House, said the Republicans' denunciations "ring hollow" as long as they continue to back Trump in the presidential race.

On Twitter, Trump responded to Obama's comments, posting, "President Obama will go down as perhaps one of the worst president in the history of the United States!"

Bucking the party

At least one Republican congressman has thrown his support behind Clinton, the Democratic nominee.

Rep. Richard Hanna, R-N.Y., became the first sitting Republican member of Congress to say publicly that he plans to vote for Clinton for president, declaring in an interview with Syracuse.com that Trump is a "national embarrassment."

The three-term congressman, who represents a swath of upstate New York near Syracuse but is not running for re-election this year, has bucked his party in the past on issues ranging from gay marriage to climate change. He declared his support for Clinton in an opinion piece published Tuesday on the news website and elaborated in an interview that Trump's remarks about the Khans were the final straw.

"I saw that and felt incensed," Hanna said in the interview. "I was stunned by the callousness of his comments."

He added: "I think Trump is a national embarrassment. Is he really the guy you want to have the nuclear codes?"

Hanna had already said he would not support Trump, a stance shared by a handful of his Republican colleagues, but he was the first congressman to throw backing to Clinton.

"In his latest foray of insults, Mr. Trump has attacked the parents of a slain U.S. soldier," Hanna wrote. "Where do we draw the line? I thought it would have been when he alleged that U.S. Sen. John McCain was not a war hero because he was caught. Or the countless other insults he's proudly lobbed from behind the Republican presidential podium. For me, it is not enough to simply denounce his comments: He is unfit to serve our party and cannot lead this country."

This week also saw Sally Bradshaw, a longtime adviser to Jeb Bush and an architect of the GOP's attempt four years ago to court younger, more diverse voters, leave the Republican Party. She said she would vote for Clinton if the race in her home state of Florida ended up being close.

"This is a time when country has to take priority over political parties. Donald Trump cannot be elected president," she told CNN.

Candidates' fundraising

With the presidential campaign fully in gear, Clinton raised $63 million in July for her White House bid, her best month yet.

In addition to her campaign money, she took in another $26 million last month for the Democratic National Committee and state parties, raising her total monthly fundraising to about $90 million.

Trump said Monday that he'd raised $35.8 million for his campaign in small donations, but he has not disclosed his full July total. Like Clinton, Trump has a fundraising partnership with party allies through which he can collect checks of hundreds of thousands of dollars from individual donors.

At a campaign event Tuesday in Virginia, Trump promised to continue writing checks to his own campaign. "I'll be in for over $100 million when it's all finished," he said. "That's a lot of money." The New York businessman already has contributed about $50 million to his effort.

Both campaigns must provide their latest fundraising details to federal regulators by Aug. 20.

The Clinton campaign said it began August with $58 million in the bank. Clinton has maintained a 700-plus-person campaign payroll and spent $35 million on television commercials between the last week of June and last week of July, according to Kantar Media's campaign advertising tracker.

Clinton notched a number of fundraising "bests" last month.

July was her first full month as the party's clear nominee, and that showed in her finances. She experienced a 75 percent increase over her previous best fundraising month, which was June, when her campaign collected $36 million. Looking back at the previous presidential race, Obama's campaign took in about $49 million in July 2012, finance records show.

Clinton has worked to build out her online fundraising operation and saw her top total in that area just last week as she officially accepted her party's presidential nomination at the party convention in Philadelphia. The campaign said she raised more than $8.7 million in the 24 hours around her speech.

Trump also has trained his attention on online fundraising, netting more than $3 million in the 24 hours after making his first email solicitation for campaign cash in June.

3 exit DNC posts

Separately, three top officials at the Democratic National Committee will vacate their posts this week over the leak of a cache of emails from the committee.

Chief executive Amy Dacey, Chief Financial Officer Brad Marshall and Communications Director Luis Miranda will leave just days after a new leader took the helm.

Nearly 20,000 emails were posted on WikiLeaks last month. They included some that raised questions about the religious faith of Clinton's primary rival, Sen. Bernie Sanders of Vermont, and others that seemed to disparage donors.

The release of the emails led DNC Chairman Debbie Wasserman Schultz to announce her resignation. Longtime Democratic strategist Donna Brazile took over as interim chairman immediately after the party's national convention ended last week.

Brazile said in a statement after the three stepped down that she was "so grateful for their commitment to this cause, and I wish them continued success in the next chapter of their career."

Officials familiar with the cache of emails have said Russian government hackers breached the committee, as well as the Democratic Congressional Campaign Committee. The FBI is investigating and attempting to determine whether emails obtained by Russia were the same ones posted on WikiLeaks.

As the DNC's chief executive, Dacey was responsible for the day-to-day operations of the party.

With the release of the WikiLeaks emails, Dacey was implicated in an exchange in which Marshall appeared to speculate about how Sanders' Jewish heritage could be used against him.

Marshall posited that he believes Sanders "is an atheist" and that it could make a difference in the Kentucky and West Virginia primaries. The messages were sent to a group that included Dacey, Miranda and another communications aide, Mark Paustenbach.

"My Southern Baptist peeps would draw a big difference between a Jew and an atheist," Marshall wrote in an email.

Dacey responded: "AMEN."

Brazile announced that she will appoint a "transition" team to be in place through the general election and until a permanent party chairman is announced.

Information for this article was contributed by Julie Pace, Erica Werner, Jonathan Lemire, Julye Bykowicz and Lisa Lerer of The Associated Press; by Isaac Stanley-Becker, Sean Sullivan, Abby Phillip and Katie Zezima of The Washington Post; and by Franco Ordonez of Tribune News Service.

A Section on 08/03/2016