(CNN) Hillary Clinton's campaign is regrouping after a weekend of stumbles left her looking vulnerable at a pivotal moment of her battle with Donald Trump.

But Sunday's drama was merely a capstone on Clinton's rough 48 hours.

Clinton aides spent Saturday cleaning up her remark that "half" of Trump's supporters were "deplorables," meaning racists, sexists and homophobes. The remark, for which she later expressed "regret," suddenly united a Republican Party that has struggled to get behind its divisive nominee.

Aides were scrambling to repair the damage Monday with Clinton's expected absence from the campaign trail for several days threatening to provide an opening for Trump to capture the initiative at a moment when he is closing in the polls.

While pneumonia is a relatively common complaint, the Democratic nominee, 68, now faces increasing political pressure to demonstrate she is fit for the considerable physical demands of the presidency. Her campaign is also confronting new questions over transparency after it kept details of her condition quiet for two days.

Trump expressed sympathy Monday when asked what he knew about Clinton's health in television interviews -- apparently seeking to avoid characteristically inflammatory remarks which would have made the story about him, rather than his rival.

"I really just don't know. I hope she gets well soon," Trump told Fox News, adding later, "Something is going on but I just hope she gets well and gets back on the trail, and we'll be seeing her at the debate."

But Trump, 70, who has made public fewer details about his health than Clinton has, could not resist raising veiled doubts about Clinton's true condition.

"They say pneumonia on Friday, but she was coughing very, very badly a week ago, and even before that, if you remember. This wasn't the first time. So, it's very interesting to see what is going on," Trump said on CNBC.

The billionaire also said during his Fox interview that he had a doctor's physical last week and would release "the numbers" when he has them.

Advisers to Clinton are discussing how to move beyond arguably the worst weekend of the campaign. Any attempt at turning the corner on transparency -- after taking reporters' questions for four-straight days last week -- "has obviously been erased," one aide said.

Health issues are always difficult territory for presidential candidates, who are forced to cede privacy that regular people take for granted. But there will still be questions asked why Clinton, after days of speculation about her health, was not more forthcoming with her diagnosis.

The health of a potential President is considered of vital public knowledge given the intense pressures of the job and concentration of powers over life and death that flow through the Oval Office.

CNN contributor and former Barack Obama strategist David Axelrod encapsulated the campaign's problem when he tweeted , "Antibiotics can take care of pneumonia. What's the cure for an unhealthy penchant for privacy that repeatedly creates unnecessary problems?"

Clinton campaign communications director acknowledged on Twitter that the campaign "could have done better," she used a pair of tweets Monday to put the focus back on their opponent.

"In contrast to HRC, Trump has been less transparent than any nominee in modern history," she tweeted

In contrast to HRC, Trump has been less transparent than any nominee in modern history. https://t.co/Q50oHK85wQ — Jennifer Palmieri (@jmpalmieri) September 12, 2016

Clinton campaign officials pushed back on the suggestion that their delay in announcing the candidate had pneumonia amounted to intentionally misleading the public, but acknowledged that Clinton herself didn't fully convey how she felt.

Many people inside the Clinton campaign did not know about the pneumonia diagnosis on Friday. An aide told CNN that Clinton "thought she could push through this ... she was feeling better" -- until Sunday morning, when she went to a September 11 memorial event in Manhattan but was forced to leave early.

Brian Fallon, Clinton's national press secretary, told CNN that the campaign will release more medical information on the candidate later this week.

"The reality is, the pneumonia is the extent of what she has been diagnosed with. There are no other undisclosed conditions," Fallon told CNN's Wolf Blitzer. He added later, "We continue to want to be as transparent as possible on this, but at some point, people have to ask the same questions of Donald Trump"

The double weekend blows came at just the wrong time for Clinton, as Trump closes in the polls and pressure builds ahead of the first presidential debate in two weeks -- an event shaping up to be a potentially pivotal moment of the campaign.

Whether Clinton's rocky weekend will turn out to be just another unexpected twist in an election season that has had everything, or exert a lasting political impact will only become clear in the coming days.

She canceled a trip to California scheduled for Monday and Tuesday, though Clinton is expected to call in to Monday's evening fundraiser. The speed of her recovery and the way her enemies handle the episode will do much to shape how voters respond to her health issue.

Both Clinton and her husband former President Bill Clinton are known for punishing public schedules, despite health issues they have both had in the past, so it would not be a surprise to see the former secretary of state seek to get back on the campaign trail as soon as possible.

Hillary Clinton isn't the only member of her campaign who has been sick with respiratory issues. Some of Clinton's top aides -- including those who travel with her -- have been felled with respiratory issues in the last month, sources tell CNN. At least three senior aides have been ill, including at least one of whom was hospitalized and treated for dehydration.

Clinton's spokesman Nick Merrill said she was feeling better on Monday but was following her doctor's recommendation to stay home and rest. Aides said the Democratic nominee would work on debate prep for her debate clash with Trump -- and event that takes on even more significance in the light of Clinton's health episode.

Weekend on defense

But a weekend on defense and a possibly reduced schedule going forward threatens to slow Clinton's campaign at an unwelcome moment and will do little to calm increasingly jittery Democrats who only weeks ago were speculating about the possibility of an electoral landslide.

Donna Brazile, the interim chair of the Democratic National Committee, released a reassuring statement late Sunday wishing Clinton a "speedy recovery."

"I look forward to seeing her back out on the campaign trail and continuing on the path to victory," she said.

It was bad enough for Clinton that she had to leave the ceremony marking the 15th anniversary of the September 11 attacks early -- setting off alarm bells among her traveling press pool. But the later emergence of video showing her wobbly, staggering and stumbling before being helped into her black van conjured up the kind of image, played over and over on television, that campaign strategists dread.

Hillary Clinton 9/11 NYC pic.twitter.com/q9YnsjTxss — Zdenek Gazda (@zgazda66) September 11, 2016

The footage was more than a blow to her dignity. It will be used by opponents to validate a months-long campaign of rumors and innuendo about the true state of Clinton's health.

Trump has frequently cast doubt on Clinton's physical fitness, saying she lacks "stamina" and takes naps in the afternoon and runs on an easy schedule -- a claim debunked by reporters who follow her campaign.

Aware of potential impact

The Clinton campaign was clearly aware of the potential impact of the video. After resting at her daughter Chelsea's apartment, the Democratic nominee emerged smiling, and under her own power in front of the cameras, taking a picture with a young girl before climbing into her motorcade.

US Democratic presidential nominee Hillary Clinton waves to the press as she leaves her daughter's apartment building on September 11, 2016.

She told reporters she was "feeling great" and parried further questions by commenting that it was a "beautiful day in New York."

The campaign also tried to foster an air of normality by saying that Clinton spent time playing with her grandchildren while at her daughter's home.

But hours of speculation and uncertainty about what happened to Clinton and a lack of information about her status triggered an air of crisis.

When details about her condition finally emerged -- in the form of a statement issued through the campaign by Clinton's physician Lisa Bardack -- they only added to impressions that the campaign abhors transparency.

Advisers to Clinton are also discussing Monday how to move beyond arguably the worst weekend of the campaign. Any attempt at turning the corner on transparency -- after taking reporters' questions for four-straight days last week -- "has obviously been erased," one aide said. Clinton campaign officials pushed back on the suggestion that they were intentionally misleading the public, but acknowledged that Clinton herself didn't fully convey how she felt.

Given that Trump is 70 and would be the oldest person to take the oath of office as President for a first term, and Clinton would be the second oldest, both candidates are certain to face pressure for a more comprehensive accounting of their health.

Bardack issued a letter late last year saying Clinton was in good health and fit to serve as President. Trump has offered only a bizarre report from New York physician Harold Bornstein, saying that he would be the "healthiest individual ever elected President."

Photos: Hillary Clinton's life in the spotlight Hillary Clinton accepts the Democratic Party's nomination for president at the Democratic National Convention in Philadelphia on July 28, 2016. The former first lady, U.S. senator and secretary of state was the first woman to lead the presidential ticket of a major political party. Hide Caption 1 of 43 Photos: Hillary Clinton's life in the spotlight Before marrying Bill Clinton, she was Hillary Rodham. Here she attends Wellesley College in Massachusetts. Her commencement speech at Wellesley's graduation ceremony in 1969 attracted national attention. After graduating, she attended Yale Law School. Hide Caption 2 of 43 Photos: Hillary Clinton's life in the spotlight Rodham was a lawyer on the House Judiciary Committee, whose work led to impeachment charges against President Richard Nixon in 1974. Hide Caption 3 of 43 Photos: Hillary Clinton's life in the spotlight In 1975, Rodham married Bill Clinton, whom she met at Yale Law School. He became the governor of Arkansas in 1978. In 1980, the couple had a daughter, Chelsea. Hide Caption 4 of 43 Photos: Hillary Clinton's life in the spotlight Arkansas' first lady, now using the name Hillary Rodham Clinton, wears her inaugural ball gown in 1985. Hide Caption 5 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons celebrate Bill's inauguration in Little Rock, Arkansas, in 1991. He was governor from 1983 to 1992, when he was elected President. Hide Caption 6 of 43 Photos: Hillary Clinton's life in the spotlight Bill Clinton comforts his wife on the set of "60 Minutes" after a stage light broke loose from the ceiling and knocked her down in January 1992. Hide Caption 7 of 43 Photos: Hillary Clinton's life in the spotlight In June 1992, Clinton uses a sewing machine designed to eliminate back and wrist strain. She had just given a speech at a convention of the International Ladies' Garment Workers Union. Hide Caption 8 of 43 Photos: Hillary Clinton's life in the spotlight During the 1992 presidential campaign, Clinton jokes with her husband's running mate, Al Gore, and Gore's wife, Tipper, aboard a campaign bus. Hide Caption 9 of 43 Photos: Hillary Clinton's life in the spotlight Clinton accompanies her husband as he takes the oath of office in January 1993. Hide Caption 10 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons share a laugh on Capitol Hill in 1993. Hide Caption 11 of 43 Photos: Hillary Clinton's life in the spotlight Clinton unveils the renovated Blue Room of the White House in 1995. Hide Caption 12 of 43 Photos: Hillary Clinton's life in the spotlight Clinton waves to the media in January 1996 as she arrives for an appearance before a grand jury in Washington. The first lady was subpoenaed to testify as a witness in the investigation of the Whitewater land deal in Arkansas. The Clintons' business investment was investigated, but ultimately they were cleared of any wrongdoing. Hide Caption 13 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons hug as Bill is sworn in for a second term as President. Hide Caption 14 of 43 Photos: Hillary Clinton's life in the spotlight The first lady holds up a Grammy Award, which she won for her audiobook "It Takes a Village" in 1997. Hide Caption 15 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons dance on a beach in the U.S. Virgin Islands in January 1998. Later that month, Bill Clinton was accused of having a sexual relationship with former White House intern Monica Lewinsky. Hide Caption 16 of 43 Photos: Hillary Clinton's life in the spotlight Clinton looks on as her husband discusses the Monica Lewinsky scandal in the Roosevelt Room of the White House on January 26, 1998. Clinton declared, "I did not have sexual relations with that woman." In August of that year, Clinton testified before a grand jury and admitted to having "inappropriate intimate contact" with Lewinsky, but he said it did not constitute sexual relations because they had not had intercourse. He was impeached in December on charges of perjury and obstruction of justice. Hide Caption 17 of 43 Photos: Hillary Clinton's life in the spotlight The first family walks with their dog, Buddy, as they leave the White House for a vacation in August 1998. Hide Caption 18 of 43 Photos: Hillary Clinton's life in the spotlight President Clinton makes a statement at the White House in December 1998, thanking members of Congress who voted against his impeachment. The Senate trial ended with an acquittal in February 1999. Hide Caption 19 of 43 Photos: Hillary Clinton's life in the spotlight Clinton announces in February 2000 that she will seek the U.S. Senate seat in New York. She was elected later that year. Hide Caption 20 of 43 Photos: Hillary Clinton's life in the spotlight Clinton makes her first appearance on the Senate Environment and Natural Resources Committee. Hide Caption 21 of 43 Photos: Hillary Clinton's life in the spotlight Sen. Clinton comforts Maren Sarkarat, a woman who lost her husband in the September 11 terrorist attacks, during a ground-zero memorial in October 2001. Hide Caption 22 of 43 Photos: Hillary Clinton's life in the spotlight Clinton holds up her book "Living History" before a signing in Auburn Hills, Michigan, in 2003. Hide Caption 23 of 43 Photos: Hillary Clinton's life in the spotlight Clinton and another presidential hopeful, U.S. Sen. Barack Obama, applaud at the start of a Democratic debate in 2007. Hide Caption 24 of 43 Photos: Hillary Clinton's life in the spotlight Obama and Clinton talk on the plane on their way to a rally in Unity, New Hampshire, in June 2008. She had recently ended her presidential campaign and endorsed Obama. Hide Caption 25 of 43 Photos: Hillary Clinton's life in the spotlight Obama is flanked by Clinton and Vice President-elect Joe Biden at a news conference in Chicago in December 2008. He had designated Clinton to be his secretary of state. Hide Caption 26 of 43 Photos: Hillary Clinton's life in the spotlight Clinton, as secretary of state, greets Russian Prime Minister Vladimir Putin during a meeting just outside Moscow in March 2010. Hide Caption 27 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons pose on the day of Chelsea's wedding to Marc Mezvinsky in July 2010. Hide Caption 28 of 43 Photos: Hillary Clinton's life in the spotlight In this photo provided by the White House, Obama, Clinton, Biden and other members of the national security team receive an update on the mission against Osama bin Laden in May 2011. Hide Caption 29 of 43 Photos: Hillary Clinton's life in the spotlight Clinton checks her Blackberry inside a military plane after leaving Malta in October 2011. In 2015, The New York Times reported that Clinton exclusively used a personal email account during her time as secretary of state. The account, fed through its own server, raises security and preservation concerns. Clinton later said she used a private domain out of "convenience," but admits in retrospect "it would have been better" to use multiple emails. Hide Caption 30 of 43 Photos: Hillary Clinton's life in the spotlight Clinton arrives for a group photo before a forum with the Gulf Cooperation Council in March 2012. The forum was held in Riyadh, Saudi Arabia. Hide Caption 31 of 43 Photos: Hillary Clinton's life in the spotlight Obama and Clinton bow during the transfer-of-remains ceremony marking the return of four Americans, including U.S. Ambassador Christopher Stevens, who were killed in Benghazi, Libya, in September 2012. Hide Caption 32 of 43 Photos: Hillary Clinton's life in the spotlight Clinton ducks after a woman threw a shoe at her while she was delivering remarks at a recycling trade conference in Las Vegas in 2014. Hide Caption 33 of 43 Photos: Hillary Clinton's life in the spotlight Clinton, now running for President again, performs with Jimmy Fallon during a "Tonight Show" skit in September 2015. Hide Caption 34 of 43 Photos: Hillary Clinton's life in the spotlight Clinton testifies about the Benghazi attack during a House committee meeting in October 2015. "I would imagine I have thought more about what happened than all of you put together," she said during the 11-hour hearing. "I have lost more sleep than all of you put together. I have been wracking my brain about what more could have been done or should have been done." Months earlier, Clinton had acknowledged a "systemic breakdown" as cited by an Accountability Review Board, and she said that her department was taking additional steps to increase security at U.S. diplomatic facilities. Hide Caption 35 of 43 Photos: Hillary Clinton's life in the spotlight U.S. Sen. Bernie Sanders shares a lighthearted moment with Clinton during a Democratic presidential debate in October 2015. It came after Sanders gave his take on the Clinton email scandal. "The American people are sick and tired of hearing about the damn emails," Sanders said. "Enough of the emails. Let's talk about the real issues facing the United States of America." Hide Caption 36 of 43 Photos: Hillary Clinton's life in the spotlight Clinton is reflected in a teleprompter during a campaign rally in Alexandria, Virginia, in October 2015. Hide Caption 37 of 43 Photos: Hillary Clinton's life in the spotlight Clinton walks on her stage with her family after winning the New York primary in April. Hide Caption 38 of 43 Photos: Hillary Clinton's life in the spotlight After Clinton became the Democratic Party's presumptive nominee, this photo was posted to her official Twitter account. "To every little girl who dreams big: Yes, you can be anything you want -- even president," Clinton said. "Tonight is for you." Hide Caption 39 of 43 Photos: Hillary Clinton's life in the spotlight Obama hugs Clinton after he gave a speech at the Democratic National Convention in Philadelphia. The president said Clinton was ready to be commander in chief. "For four years, I had a front-row seat to her intelligence, her judgment and her discipline," he said, referring to her stint as his secretary of state. Hide Caption 40 of 43 Photos: Hillary Clinton's life in the spotlight Clinton arrives at a 9/11 commemoration ceremony in New York on September 11. Clinton, who was diagnosed with pneumonia two days before, left early after feeling ill. A video appeared to show her stumble as Secret Service agents helped her into a van. Hide Caption 41 of 43 Photos: Hillary Clinton's life in the spotlight Clinton addresses a campaign rally in Cleveland on November 6, two days before Election Day. She went on to lose Ohio -- and the election -- to her Republican opponent, Donald Trump. Hide Caption 42 of 43 Photos: Hillary Clinton's life in the spotlight After conceding the presidency to Trump in a phone call earlier, Clinton addresses supporters and campaign workers in New York on Wednesday, November 9. Her defeat marked a stunning end to a campaign that appeared poised to make her the first woman elected US president. Hide Caption 43 of 43

Clinton is likely to resume campaigning Wednesday, but will almost certainly not fly to Nevada. She is more likely to give her economic-themed speech in a battleground state far closer to New York: Pennsylvania, New Hampshire and Ohio are possibilities.

Difficult territory for candidates

Ever since Clinton sustained a blood clot and a concussion after a fainting episode near the end of her tenure as secretary of state in 2012, she has faced a swirl of conspiracy theories about her health.

She joked about the criticism on ABC's "Jimmy Kimmel Live" last month.

JUST WATCHED See Hillary Clinton laugh off health questions Replay More Videos ... MUST WATCH See Hillary Clinton laugh off health questions 01:45

"Back in October, the National Enquirer said I would be dead in six months. So with every breath I take, I feel like I have a new lease on life," Clinton said.

If Clinton is forced to take time off, it will fall to her high-profile surrogates to pick up the slack. The President, for instance, is due to campaign for his former rival and secretary of state Tuesday in Philadelphia. His wife, Michelle Obama, will hit the campaign trail as well next week.

Clinton had hoped for better headlines after the first frenzied post-Labor Day week on the trail.

After months of dodging the press, she invited reporters to travel on her new campaign jet last week and took questions. On Friday, she gathered a group of high ranking former national security officials and military brass and delivered a presidential-style statement to stress her suitability to lead national security policy in the Oval Office.

Polls, however, show that Clinton's lead has dramatically narrowed in recent weeks, amid unflattering coverage of the controversy over her email server and the Clinton Foundation.

A CNN/ORC poll last week had behind Trump by 2% among likely voters and there are also signs of tightening in swing state polls -- despite Clinton still having many more routes to 270 electoral votes than Trump

But in one ray of sunshine for Clinton on Sunday, an ABC News/Washington Post poll showed her up 5% on Trump among likely voters.