Washington (CNN) President Donald Trump's optimistic statements about the coronavirus are increasingly being undermined by more alarming comments from public health officials in his own administration and warnings the outbreak is now certain to reach US soil.

While Trump is reassuring the nation that the virus is "going to go away" and is "very well under control," stock markets that he uses as a barometer of his administration's success tank, and health experts are painting a far more dire picture, even suggesting that a pandemic is getting closer.

A top US Centers for Disease Control and Prevention vaccination expert warned Tuesday that the virus could bring severe disruption to American life, affecting schools and businesses, and told people to get ready now.

The disconnect between Dr. Nancy Messonnier's comments and Trump's stance raised doubts about the coherence of the administration's response and the question of how the President will respond, given his history of turning on officials who contradict his views with evidence-based reasoning.

CNN's Kaitlan Collins and Kevin Liptak reported Wednesday that the President has been publicly downplaying the possible effects of the virus on the United States to avoid provoking further panic in the markets but that he has been frustrated with officials warning about the unknowns of the virus's possible spread.

Another official, Anthony Fauci, the head of the National Institutes of Allergy and Infectious Disease, told CNN's "New Day" Wednesday that Messonnier was reflecting the spread of coronavirus through countries like Italy, Iran and South Korea.

"When that happens, then you have the makings of a pandemic," Fauci said. "What she was saying was that being the case, if we have a pandemic, almost certainly we are going to get impacted."

Dr. Anne Schuchat, principal deputy director of the CDC, meanwhile told ABC News that the way that the epidemic was spreading could soon challenge US efforts to contain it.

"We recognize that our very strong measures here in the United States to contain the virus, to keep it limited to very low numbers, may not hold for the long haul," Schuchat said.

Trump tweeted shortly after returning home from India on Wednesday that he had a meeting on the virus planned later in the day and that his staff were all doing a "great job." He announced Wednesday morning that he will hold a news conference at the White House about coronavirus at 6 p.m. ET.

Nervousness on Capitol Hill was exacerbated by a string of developments that appeared to reflect Messonnier's assessment of the situation better than the President's rosier commentary. The CDC said Tuesday night that coronavirus was not recognized to be spreading inside the United States. It said if sustained transmission did occur, its strategy would call on those infected to stay home from work. School dismissals and the cancellation of mass meetings might be necessary as well as telecommuting for office workers.

The mayor of San Francisco declared a state of emergenc y to prepare for the possible arrival of the virus. Questions about the government's capacity to monitor widespread outbreaks deepened when it emerged that only 12 state and local health laboratories can test for Covid-19. Another stocks sell-off provoked by concern about the disease's quickening wiped another 900 points fr om the Dow Jones Industrial Average. Trump's assurance that a vaccine is close appeared to be born from the same sense of hope that led him to predict that warming temperatures in the spring will snuff out the virus.

To date, there are 57 recorded cases of coronavirus in the United States, including 40 passengers who were aboard the Diamond Princess cruise ship in Japan, three people who were brought home from China and 14 other patients. Meanwhile, the virus is grabbing a stronger foothold in Europe and Asia.

So far, Trump's political interests appear to have led the President to seek to minimize the threat from the virus and the chances of it evolving into an epidemic on American soil.

But fast-moving developments mean that Trump looks behind the curve of the growing threat to the United States -- a dangerous position for a President who is seeking a second term. Democrats, apparently looking for vulnerabilities, are warning that his administration is asleep as a possible pandemic builds.

In the next few days, the President's political interests may dictate a far more proactive attitude, given that a crisis that rages out of control could taint his White House with a reputation for incompetence.

Behind the scenes, the President is frustrated

Privately, the President may have come to that conclusion already. CNN reported Tuesday that Trump was becoming frustrated with his administration's response to the situation and that officials were beginning to acknowledge that the epidemic was going to become a greater problem than first thought.

Given the torrent of foreboding news, as coronavirus emerged as a greater threat in Europe and the global death toll reached 2,763, Trump's upbeat assessment delivered in New Delhi appeared to have aged badly.

The President said the coronavirus situation was "very well under control in our country." And he added "that whole situation will start working out." Trump also hit at Democratic Senate Minority Leader Chuck Schumer, who blasted the White House's emergency $1.25 billion funding request as "too little, too late."

On Air Force One, Trump tweeted that "if I asked for more he would say it is too much. He didn't like my early travel closings. I was right. He is incompetent!"

Other White House officials tried to play down a building sense of dread -- an important role in a time of crisis -- as long as such confidence reflects reality.

Top White House economic adviser Larry Kudlow said on CNBC that the virus was "very contained" in the United States and that health experts were prepared for all eventualities. The administration says it has got its best brains working on the virus and said Trump has taken part in multiple meetings and briefings on the situation.

"I would echo the words of the WHO that said don't overreact. My own view is don't panic. I'm an old guy, been around a long time, I've seen these things come and go," Kudlow said.

Schumer said that he hoped that the administration's optimistic forecasts about the coronavirus situation were not intended to juice stocks but added: "When Larry Kudlow says it's contained you get to wonder what the motivation is."

The message coming from appointees in the government's health infrastructure is far less reassuring than that voiced by Trump's political subordinates in the West Wing.

"The data over the past week about the spread in other countries has raised our level of concern and expectation that we are going to have community spread here,"the CDC's Messonnier told reporters on a conference call.

Messonnier said it was not known when coronavirus would take root in the US and how dangerous it might be. But she warned: "Disruption to everyday life might be severe," adding that schools and families should begin to prepare now.

"It's not so much a question of if this will happen any more, but rather, more a question of exactly when this will happen and how many people in this country will have severe illness."

Concern on both sides of the aisle

Concern about coronavirus is becoming one of the rare issues that crosses party lines in polarized Washington.

Republican Sen. John Kennedy of Louisiana confronted the acting Homeland Security Secretary Chad Wolf about the virus in the Senate Appropriations sub-committee.

"You're supposed to keep us safe. The American people deserve some straight answers on the coronavirus and I'm not getting them from you," Kennedy said, after asking about transmission of the disease and levels of preparedness.

Wolf told reporters after the hearing that his department was "extremely focused."

"We're implementing a number of operational measures at airports, seaports and land ports of entry," he said.

Senators attended a classified briefing on Tuesday morning with DHS, HHS and CDC officials about the progress of a vaccine, supply chain issues and the possibility of a spike in cases of coronavirus within US borders.

But senators in both parties cast doubt on the readiness of the administration.

"It's completely inadequate to the threat that exists. A real, present danger of outbreaks in the United States," Connecticut Democratic Sen. Richard Blumenthal said.

This story has been updated to include additional reporting and reaction.