Government response updates: Trump calls himself a 'wartime president,' promises 'total victory' He also denied that his calling the disease the "Chinese virus" is racist.

President Donald Trump on Wednesday started his latest briefing to the nation on the government response to the coronavirus crisis by saying, "I would like to begin by announcing some important developments in our war against the Chinese virus," again casting the effort in military terms and referring to the disease with a term that has sparked backlash.

At one point, Trump called himself "in a sense, a wartime president."

Trading on Wall Street was halted as Trump spoke when circuit breakers kicked in as the Dow plunged.

He announced he was signing the Defense Production Act, which gives him the power to direct civilian businesses to help meet orders for products necessary for the national defense, in addition to deploying two Navy hospital ships. He said one would go to New York -- the state with the most cases of COVID-19.

He later said on Twitter that while he signed the act, he would only "invoke it in a worst case scenario in the future."

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With regard to his proposal to send direct payments to Americans to stimulate the economy and help workers losing jobs -- checks that an administration official said could be $1,000 or more -- Trump said the amount is "to be determined."

"We are looking at different numbers. We are looking at timing that would be different. Splitting the time, splitting the payments. We are looking at a lot of different things. It hasn't been determined yet but it will surely be determined," before repeating a phrase he used in Tuesday's briefing, "Everybody seems to want to go big."

The president also announced that the Department of Housing and Urban Development is "providing immediate relief to renters and homeowners by suspending all foreclosures and evictions until the end of April." However, HUD announced after the briefing that the suspension applies only to single family homeowners with a FHA-insured mortgage, not renters.

Trump also said he planned to invoke a provision of the federal legal code that would allow the federal government to prohibit the entry of asylum seekers because of COVID-19.

The new measures come as the number of U.S. cases of the novel coronavirus jumped overnight to nearly 6,000 across all 50 states and as Americans enter the third day of a 15-day critical period meant to "flatten the curve" of the virus spread.

Here are Wednesday’s most significant developments in Washington:

Trump calls himself a 'wartime president,' defends calling disease 'Chinese Virus'

Trump, Mnuchin propose sending relief checks directly to Americans as some in Congress support

Trump has a phone call with physicians and a briefing with nurses on the coronavirus response

Trump says he'll hold news conference on the Food and Drug Administration's response to COVID-19 Thursday

Senate passes coronavirus relief measure, bill now heads to Trump's desk

Here is how developments unfolded on Wednesday.

Trump announces new military-related measures in "war" against COVID-19

"We’ll be invoking the Defense Production Act, just in case we need it," Trump said. "In other words -- I think you will know what it is -- and it can do a lot of good things if we need it, and we will have it all completed, signing it in just a little while, right after I'm finished with this conference. I'll be signing it," he said, giving him the power to direct civilian businesses to help meet orders for products necessary for the national defense if invoked.

"We are sending, upon request, the two hospital ships. They are being prepared right now. They are massive ships. They’re the big white ships with the red cross on the sides. One is called the Mercy and the other is called the Comfort. And they are in tip-top shape," he said.

"Now it's our time. We must sacrifice together, because we are all in this together, and we will come through together. It's the invisible enemy. That's always the toughest enemy," Trump said. "But we are going to defeat the invisible enemy. I think we are going to do it even faster than we thought, and it'll be a complete victory. It'll be a total victory."

Birx acknowledges dire reports for young people

Ambassador Deborah Birx, the White House response coordinator on the coronavirus, raised concerns about reports coming out of Italy and France showing "some young people getting seriously ill and very seriously ill in the ICUs."

"We have not seen any significant mortality in the children, but we are concerned about the early reports coming out of Italy and France," Birx said. "Even if it's a rare occurrence, it may be seen more frequently in that group, and be evident now."

Birx suggested that this uptick in younger people becoming seriously ill may be the result of that age group in Italy and France having taken fewer precautions to protect themselves because the early data out of China suggested they were less at risk compared to older people.

"We think part of this might be that people heeded the early data coming out of China and coming out of South Korea, that the elderly or those with pre-existing medical conditions were at particular risk," she said.

Birx went on to again implore the millennial generation to follow the government's social distancing guidance.

"So, again, not only calling on you to heed what is in the guidance, but to really ensure that each and every one of you are protecting each other."

She also took a moment to address the mortality rate.

"If you look at all of the countries to date, the mortality is higher at the beginning because you are diagnosing the sickest, the ones who came in quite ill," Birx continued on Wednesday. "You are seeing mortality or deaths today from infections that occurred 2-3 weeks ago, in general."

Dr. Anthony Fauci, the nation's leading expert on infectious diseases cautioned Tuesday it will take "several weeks and maybe longer until we know we're having an effect," on slowing the spread of the virus but said if Americans follow the 15-day guidelines, young people especially, "we're going to see a hump instead of a peak."

Trump says self-swab testing is being developed

"Today I can announce further steps expand testing capacity. We are working with several groups to determine if the self-swab, the much easier process than the current process that is not very nice to do. I can tell you, because I did it it," Trump said.

He said that it "would be administered also by a health official, but it would be a lot easier to do."

Later, he clarified that the FDA has not approved the self-swab test he mentioned at the start of the briefing, but "they are looking down the line and they are looking at it very seriously."

Proceeding to again blame previous administrations, Trump said, "Nothing has been so contagious. The level of contagion has been incredible, actually. Nobody's seen anything quite like this."

"We've inherited a very obsolete system. This was a system that was out of date, obsolete, it was a system that was never meant to take care of the kind of quantity."

"If you go back to years past, even recently, like the flu -- nobody had tests before. They didn't test the entire nation to see whether or not they had the flu. They got the flu. They got better," Trump said. "Now all now all of a sudden they do this very complex testing."

Trump pressed on calling disease "Chinese Virus'

Asked by ABC News Senior White House Correspondent Cecelia Vega if his use of the term "Chinese Virus" is racist, Trump said, "it's not racist at all."

"It comes from China, that's why. It comes from China. I want to be accurate," he continued. "China tried to say at one point that -- maybe they've stopped now, that it was caused by American soldiers. That can't happen. It's not going to happen. Not as long as I'm president. It comes from China."

Asked whether he thought China should be "punished," Trump answered, "I don't know if you would say China is to blame. Certainly, we didn't get an early run on it," Trump said. "It would have been helpful if we knew about it earlier. But it comes from China. It's not a question."

When Vega asked him to clarify, Trump said, "I don't believe they are inflicting" the virus on the U.S., but "I think they could have given us a lot earlier notice, absolutely."

"We would have had a lot of dead people like we haven't seen before," Trump said, if he hadn't acted to limit travel from China.

Trump says 20 percent unemployment is "total worst case"

Trump also told Vega that a potential 20 percent unemployment rate, as floated by Treasury Secretary Steven Mnuchin as an argument to Senate Republicans to get a stimulus package passed quickly, is a "total worst case" scenario and that the U.S. is "nowhere near it."

"Well, I don't agree with that. No, I don't agree, Trump said. "That's an absolute, total worst-case scenario. No, we don't look at that at all. We are nowhere near it."

"We had the best economy we've ever had, and then one day you have to close it down in order to defeat this enemy. But we are doing it, and we are doing it well. I tell you, the American people have been incredible. For the most part they been really incredible."

"When I use the word 'calm,' that doesn't mean I'm not taking it seriously. We should be calm. We should be extremely calm," Trump said, amid criticism that his administration didn't take the virus seriously from the onset, inhibiting the government's response to it.

Trump says he will use crisis powers to stop asylum seekers at southern border; US and Canada close close border

He also said at the briefing he planned to invoke a provision of the federal legal code that would allow the federal government to prohibit the entry of asylum seekers because of COVID-19.

"42 U.S. Code § 265" lets the U.S. Surgeon General block people from entering the country to fight the risk of a "communicable disease."

Asked if he’d invoke that, Trump replied, "The answer is yes."

He said that would happen "very soon, probably today."

Trump said he didn’t plan to close the U.S. border with Mexico like he did with Canada.

"No, we’re not going to close it. But we are invoking a certain provision that will allow us great latitude as to what we do," Trump said.

President Trump tweeted Wednesday morning that by "mutual consent" the U.S. will be temporarily closing the northern border with Canada to non-essential traffic, adding that trade will not be affected.

Trump teases big announcement on the FDA, stimulus checks to American people

During his opening remarks at a meeting with members of the White House coronavirus task force and representatives of American nurses in the late afternoon, Trump announced his news conference on new measures the Food and Drug Administration is taking in the "war" again coronavirus will take place Thursday.

Earlier Wednesday, Trump tweeted about "very important news from the FDA" and touted his response to the novel coronavirus -- telling Americans, "money will soon be coming to you" -- after the White House proposed a $1 trillion economic stimulus package, including a measure to send checks to directly to Americans.

The White House late Tuesday night also requested $45.8 billion more from Congress -- in addition to the trillion-dollar package currently being negotiated -- in order to cover unanticipated costs for an array of federal agencies fighting COVID-19.

The $1 trillion stimulus spending breaks down as follow: $500 billion for two rounds of $250 billion of direct payments for Americans to go out around April 6 and May 18; $300 billion to help small businesses meet payroll; $50 billion for the airlines; and $150 billion for loans and loan guarantees for other parts of the economy.

Trump continues to call COVID-19 "the Chinese Virus" in tweets

In a series of Wednesday morning tweets, the president continued to referred to the novel coronavirus as "the Chinese Virus" -- despite the Chinese government criticizing the terminology and his own health officials warning that doing so promotes hate incidents against Asians.

Secretary of Health and Human Services Alex Azar told Congress last month, "Ethnicity is not what causes the novel coronavirus."

Census pulls back on field operations for at least two weeks

Just one week after the 2020 census officially kicked off and invitations arrived in U.S. mailboxes, the bureau announced it’s having to pause field operations for two weeks.

"In late May, census takers around the nation will begin visiting households that have not yet responded to the 2020 Census to help complete the count," the Census Bureau said in a statement. "As we continue to monitor the evolving COVID-19 outbreak, we will adjust census taker and survey operations as necessary in order to follow the guidance of federal, state and local health authorities."

The statement went on to encourage the public to respond to the census online, by phone or mail.

City leaders encourage colleagues and communities to act responsibly

The president of the National League of Cities, Los Angeles City Councilmember Joe Buscaino, is demanding action from local leaders as calls have intensified to stem the coronavirus crisis now playing out across the globe.

Buscaino, in a statement to ABC News, called on his fellow leaders from coast to coast to lead the charge in curbing COVID-19’s spread, and encourage their communities to act responsibly.

“Local leaders across America are on the front lines of this unprecedented crisis,” Buscaino said. “I implore those cities who have not taken action, to immediately take steps to close schools, restrict access to public spaces, and ask people to ‘shelter in place.’”

“This is not a drill. We must act urgently.”

An aide familiar with the League said an alarm must be sounded to compel colleagues to act with a greater sense of exigence.

It comes just days after multiple sources told ABC News an emergency meeting to work on a resolution asking the Trump administration to call for a national shutdown of in-dining restaurants and bars did not come to fruition for the group.

Buscaino now looks to “lead with urgency,” calling for FEMA and the Army Corps of Engineer to build infrastructures for additional intensive care unit beds that may soon be of vital need.

What to know about coronavirus:

How it started and how to protect yourself: coronavirus explained

What to do if you have symptoms: coronavirus symptoms

Tracking the spread in the US and Worldwide: coronavirus map

ABC News' Anne Flaherty, Ben Gittleson, Jordyn Phelps, Sasha Pezenik and Jack Arnholz contributed to this report.