Democratic presidential candidate Hillary Clinton. AP Photo/Andrew Harnik Hillary Clinton canceled several events scheduled for early this week as her campaign attempted to battle concerns about her health, while also taking fire for a recent remark she made about Donald Trump's supporters.

The Clinton campaign went into full damage-control mode after a video surfaced of the Democratic presidential nominee having difficulty walking while leaving a 9/11 memorial service in New York on Sunday. Several hours after the video was published, her physician released a letter revealing that the former secretary of state contracted pneumonia, which caused her to get overheated during the 9/11 memorial event.

The disclosure frustrated some reporters who felt Clinton's campaign purposefully obfuscated her illness while simultaneously adding fuel to speculation about Clinton's health, which has been a fixation of mainly fringe right-wing media outlets for months.

"How they handled today was not good," said Evan Siegfried, a Republican strategist and author of "GOP GPS." "Three different responses prior to pneumonia. Had they come out with it at first it would have quelled the chatter."

Many Democrats, like former Obama spokesman Dan Pfeiffer, rebuked concerns about Clinton's health, noting the normality of candidate illnesses and Clinton's packed campaign schedule.

Clinton was the first major 2016 presidential candidate to disclose some of her health records, releasing a note from her doctor in 2015 detailing her hypothyroidism and recovery from a 2012 concussion. For his part, Trump has publicly released only a hastily written letter from his gastroenterologist proclaiming the Republican presidential nominee "will be the healthiest individual ever elected to the presidency."

The pneumonia incident came at the end of one of the roughest recent weekends for the Clinton campaign since it opened up a notable lead of Trump in the polls following the Democratic National Convention in July. National polls show the race tightening, with Clinton's lead shrinking to three points in the RealClearPolitics average of recent polls, while in battleground states like Florida and Iowa, Trump holds a slight lead.

On Friday, the former secretary of state amended comments from a gala in New York in which she characterized half of Trump's supporters as prejudiced in some form.

"To be grossly generalistic, you could put half of Trump's supporters into what I call the basket of deplorables. Right? The racist, sexist, homophobic, xenophobic, Islamophobic — you name it. And unfortunately there are people like that. And he has lifted them up," Clinton told an audience during a speech about protecting LGBT rights.

Though Clinton said that she regretted generalizing, and empathized with many Trump supporters experiencing economic hardship, Trump quickly condemned his rival's dismissal of his supporters, saying that she showed "bigotry" and "hatred for millions of Americans."

"How can she be President of our country when she has such contempt and disdain for so many great Americans?" Trump said. "Hillary Clinton should be ashamed of herself and this proves beyond a doubt that she is unfit and incapable to serve as President of the United States."

Clinton with New York City Mayor Bill de Blasio at a 9/11 memorial event on September 11, 2016. AP Photo/Andrew Harnik

Matthew Mackowiak, president of Potomac Strategist and a vocal critic of Trump and Clinton, said the campaign's handling of Clinton's pneumonia and the "deplorables" comment "gives Trump the chance to make her play defense."

"The bizarre communications failure exhibited by her campaign has united the Trump campaign and the media, which was an impossible task," Mackowiak said.

He added: "I don't necessarily think that 'deplorables' comment or the health scare are a 'voting issue,' but the net impact will be further tightening of the polls, Hillary on defense, and a virtuous cycle for Trump, all leading into the first debate."

But some on the left think Clinton's comments may not be bad for the campaign in the long run.

Mo Elleithee, the executive director of the Georgetown Institute of Politics and Public Service, told Business Insider that when Trump is talking about the behavior of supporters who express racist sentiments, he's reminding some voters who remain on the fence that they're joining ranks with voters with questionable biases.

"The Trump campaign is falling into a trap. They said they're making this the focus of the week. If that means we're spending the next week talking about how many racists are supporting Trump and why, then the Clinton folks should be pretty happy," Elleithee said in an email.

Former Obama adviser Steve Schale says he's "honestly not convinced anything matters," saying that he doubts many voters convinced of conspiracy theories about Clinton's health will be swayed by notes from her doctor.

"Voters have largely gone to their camps, meaning there are only a handful of voters still up for grabs. For many of these folks, much of this day to day is just noise," Schale said.

He added: "The debates are an important moment. It is her chance to look strong and composed, and it is his chance to convince voters that he can be president. That first debate in New York will mean far more than anything either candidate has done over the last few weeks."