Trump advisers grilled on coronavirus as lawmakers receive mixed messages on what happens next A top Senate Republican sternly warned Trump advisers it's 'time to step up.'

With an uptick in coronavirus cases in the U.S. expected to rise, lawmakers on Tuesday hammered President Donald Trump’s top advisers on whether the administration was doing enough almost two months into the global crisis, expressing deep skepticism of the president’s claims that the situation was “under control."

Democrats and some Republicans sharply questioned whether the administration's $2.5 billion spending plan was enough to combat the virus, and asked repeatedly about a shortage of millions of face masks for health care workers that would be needed in the virus spread.

One top Republican senator issuing a stern warning.

“This is not the time to try to shortchange the American people … This is the time to step up,” said Sen. Richard Shelby, R-Ala., of the latest spending plan.

The Trump administration responded with mixed messages on the health scare -- insisting the threat was "contained" while simultaneously acknowledging that more people inside the U.S. would likely turn up infected.

"It looks like they're getting it under control, more and more, they're getting more and more under control," Trump said Tuesday morning at a news conference in India. "So, I think that's a problem that's going to go away."

They noted that US-based cases have remained steady and that the number hasn't been rising -- a data point political appointees hailed as a success, even as other officials at the Centers for Disease Control and Prevention predicted that the virus would inevitably spread rapidly through the U.S.

"That is a remarkable level of containment here in the United States," Health and Human Services Secretary Alex Azar told reporters at a press conference Tuesday, later adding that "we are realistic" there would be more cases.

Several Republicans said they were confident the Trump administration was handling the situation. But others said they were frustrated, insisting they received a different message at a closed-door briefing earlier that day with the nation's premier health experts. Democratic Sen. Patty Murray of Washington said they were told that “there is a very strong chance of an extremely serious outbreak of coronavirus in the United States.”

In a hearing with Homeland Security Secretary Chad Wolf, Republican Sen. John Kennedy of Louisiana grew visibly agitated that the Cabinet secretary couldn't say what U.S. models were predicting or whether health care workers had the right equipment.

“You’re head of Homeland Security. Do we have enough respirators or not?” Kennedy told Wolf, who deferred questions on the scope of the crisis and preparedness plans to the Health and Human Services Department.

"The American people deserve some straight answers on the coronavirus and I'm not getting them from you," Kennedy said at one point.

In a separate hearing, Azar testified that the nation's health care workers would need 300 million masks -- and that there's only some 30 million in stock. He said that's why the administration devised its $2.5 billion spending plan, which includes a request for $1.25 billion in new emergency cash.

Azar also said that while containment was still the goal, “at some point, if there is some sustained human-to-human transport, we hope to mitigate."

Democrats accused Trump of taking the threat seriously only after a fall in the stock market over the last two days -- the worst two-day stretch in two years.

“I'm just wondering why it took a dive in the stock market before the Trump administration decided this was an important issue, important enough to ask for this money,” Democratic Sen. Dick Durbin of Illinois told reporters.

“We should have emergency preparedness, not that we have an emergency in America, but we have to prepare to make sure we don’t,” Sen. Joe Manchin of West Virginia said. “And that's what we're not doing.”

In a floor speech, Senate Democratic Leader Chuck Schumer blasted the administration for what he called “towering and dangerous incompetence.”

Meanwhile, a top health official warned the spread of the virus was inevitable.

“It’s not a question of if this will happen but when this will happen and how many people in this country will have severe illnesses,” said Dr. Nancy Messonnier, a top health official at the Centers for Disease Control and Prevention.

"I told my children at breakfast today that although risk is low we need to be preparing for significant disruption to our lives," Messonnier later added.

During his news conference, Trump said that while the coronavirus is "pretty bad" and a "very serious thing," he said that "it's going to work out fine" and that the virus will "go away."

ABC News' Allison Pecorin, Eric Strauss, Trish Turner, Sophie Tatum and Jordyn Phelps contributed to this report.