WASHINGTON (AP) — Washington is straining for an ample response to the coronavirus outbreak that is testing the nation's political and health care systems after President Donald Trump restricted air travel from Europe, Congress ran into trouble approving an aid package and the centers of power — the domed Capitol and stately White House — are being shuttered to visitors.

Trump, in an Oval Office address to the nation Wednesday night, said the monthlong restriction on travel would begin late Friday at midnight. After days of playing down the threat, he blamed Europe for not acting quickly enough to address the "foreign virus" and claimed that U.S. clusters were "seeded" by European travelers.

But he said Thursday that he is also considering restricting travel to domestic hot spots such as California and Washington state. "Is it a possibility? Yes," he said. The president also said he would postpone campaign rallies, telling reporters that he believes he needs a "little separation until such time as this goes away."

As classes, sports events, concerts and conferences are canceled across the nation, Trump also proposed postponing this summer's Olympics in Japan for a year.

So far, the administration's haphazard response and the stalemate in Congress have resulted in more uncertainty as the crisis roils the financial markets and rewrites daily life for Americans.

House lawmakers expressed alarm Thursday after a private briefing with Dr. Anthony Fauci, the National Institute of Health's infectious disease chief, and other public health officials, Lawmakers were particularly frustrated that U.S. officials have tested relatively few patients suspected to be infected.

"We're basically, in my opinion, flying blind," said Rep. Susie Lee, D-Nev. Others described the meeting as heated, testy with many lawmakers leaving flooded with graver concerns about the administration's response.

"We should be exuding confidence nationally," said Rep. Anna Eshoo, D-Calif. "The confusion is damaging."

Congress decided to shut the Capitol to the public until April. Congressional office buildings and the Congressional Visitor Center, through which tourists enter the Capitol, were also being closed. Only lawmakers, staff, journalists and visitors with official business will be permitted to enter. White House tours have been temporarily suspended.

The Smithsonian said it was canceling all public events, programming and gatherings, including rental of its facilities, through May 3. The Smithsonian's network of museums and the National Zoo will remain open for now.

The financial markets around the world took more hits Thursday. The S&P 500 was down 7%, as of 10:15 a.m. after trading was temporarily halted following a steep drop in the first few minutes of trading. The index is set to join the Dow in entering a bear market after losing more than 20% from its record set last month, and one of the greatest eras in Wall Street's history is crumbling. The Dow was off about 1,800 points, or close to 8%.

For most people, the new coronavirus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia.

The vast majority of people recover from the new virus. According to the World Health Organization, people with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover.

Trump said the U.S. travel restrictions won't apply to the United Kingdom, and there would be exemptions for "Americans who have undergone appropriate screenings."

The State Department issued a global health advisory cautioning U.S. citizens to "reconsider travel abroad" due to the virus and associated quarantines and restrictions.

Congress's multibillion-dollar aid package from Democrats was being halted by Republicans before a hoped-for vote Thursday. "Right now we have to find our common ground to work together to get this done as soon as possible," said House Speaker Nancy Pelosi, D-Calif.

Trump said he would not support the measure "because there are things in there that have nothing to do with what we're talking about." He did not go into detail.

The bill would build on last week's $8.3 billion emergency coronavirus measure and provide free testing, a new federal sick pay program, more unemployment insurance and food aid for workers and other Americans hit by the crisis.

The package would create a federal sick pay program, providing up to three months of partial pay, for those stricken or caring for those ill from the virus.

It would required health insurance companies to provide free testing for the virus and eliminates cost-sharing requirements such as co-payments for Medicare and Medicaid patients. There's more than $1 billion in food aid for the poor and senior citizens, including money to replace school lunch benefits for children whose schools have closed. It has $1 billion in extra money for unemployment pay, for the newly jobless.

Senate Majority Leader Mitch McConnell, R-Ky., called it "an ideological wish list" that Republicans would oppose.

While Trump said all European travel would be cut off, Homeland Security officials later clarified that the new travel restrictions would apply only to most foreign nationals who have been in the "Schengen Area" at any point in the 14 days prior to their scheduled arrival to the United States. The area includes France, Italy, German, Greece, Austria, Belgium and others, and the White House said the zone has the highest number of confirmed COVID-19 cases outside of mainland China.

The restrictions don't apply to legal permanent residents, immediate family of U.S. citizens or others "identified in the proclamation" signed by Trump. Vice President Mike Pence said Thursday on ABC's "Good Morning America" that the administration is also requesting travelers returning to the U.S. from Europe to "voluntarily quarantine" for 14 days.

But some health officials, and even a former high-ranking Trump administration official, suggested that Trump's European travel restriction was futile because the virus is already widespread on U.S. soil.

"In two weeks, we will regret wasting time and energy on travel restrictions and wish we focused more on hospital preparation and large scale community mitigation," Trump's former homeland security adviser, Thomas Bossert, tweeted Thursday.

The Oval Office address represented an abrupt shift in tone from a president who has repeatedly sought to play down the severity of the virus outbreak. Even as Trump spoke from behind the Resolute Desk, the pandemic's ferocious rewriting of American daily life continued. The National Basketball Association suspended its season, and Oscar-winning actor Tom Hanks announced that he and his wife, Rita Wilson, had tested positive for COVID-19. The first confirmed case on Capitol Hill was reported in a legislative staffer.

The White House has scrapped a planned trip by the president to Nevada and Colorado this week, "out of an abundance of caution." Trump's reelection campaign also postponed an event next Thursday in Milwaukee that was to feature the president.

Trump, 73, is considered at higher risk because of his age and has repeatedly flouted the advice of public health experts, who have advised the public to stop hand-shaking and practice social distancing.

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Associated Press writers Aamer Madhani, Lauran Neergaard, Martin Crutsinger, Laurie Kellman and Kevin Freking in Washington contributed to this report.

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