(Adds Trump tweet, State Department travel)

By Alexandra Alper and Deborah Bloom

WASHINGTON/SEATTLE, March 11 (Reuters) - The Trump administration was set on Wednesday to discuss new restrictions on travelers from European countries to fight coronavirus, sources said, as a top U.S. health official warned that the pandemic "is going to get worse" in the United States after ravaging China, Italy and other countries.

The potential new measures could mirror a ban on travel to the United States imposed on foreigners who visited China in the prior two weeks, which was later extended to Iran, sources familiar with the discussions said. Advisories recommending Americans cancel travel to certain European countries are also under consideration, the people said.

In Washington state, Governor Jay Inslee prohibited gatherings of over 250 people in three Seattle-area counties and said he may soon close schools to slow the spread of coronavirus as the state suffered the deadliest outbreak in the United States.

The Trump administration is exploring cutting taxes to protect the economy, Democratic presidential candidates are cancelling events and New York's governor said the federal government had "fallen down on the job" as officials scrambled to fight the coronavirus outbreak.

It was not immediately clear whether the White House would announce travel measures on Wednesday, but one source said new travel advisories could possibly be disclosed.

Two weeks ago, the State Department issued a travel advisory calling on U.S. citizens to reconsider travel to Italy, where authorities said on Wednesday the death toll from the outbreak had jumped 31% to 827 in 24 hours.

The World Health Organization described the coronavirus, which causes a respiratory illness that can be fatal, as a pandemic on Wednesday for the first time.

Anthony Fauci, head of infectious diseases at the National Institutes of Health, told a congressional hearing that the outbreak would only get worse in the United States.

"We will see more cases and things will get worse than they are now. How much worse they will get will depend on our ability to do two things: To contain the influx of people who are infected coming from outside and the ability to contain and mitigate within our own country," Fauci told the House of Representatives Oversight Committee.

"Bottom line: It's going to get worse," Fauci said.

Washington state's ban on gatherings was aimed at sports, concerts, worship services and other events, Inslee told a news conference.

The Pacific Northwest state has reported over a quarter of the U.S. coronavirus cases and nearly all the deaths, putting pressure on Inslee to slow the virus' spread to prevent hospitals from being overwhelmed.

Treasury Secretary Steven Mnuchin said the Trump administration was looking into taking steps that could put hundreds of billions of dollars into the U.S. economy to shield it from a slowdown brought on by the disruption from coronavirus.

Health Secretary Alex Azar said federal leaders were working with local officials in the hardest-hit states, saying "strong mitigation steps" could help buy valuable time.

The governor of New York, however, said federal officials had left states scrambling to act on their own, including ramping up testing for the highly contagious respiratory illness.

"We can't wait for the federal government because it's not going to happen," said Andrew Cuomo. "The federal government has just fallen down on the job," Cuomo, a Democrat, told MSNBC, adding that he had told other state governors, "You're on your own."

The number of U.S. coronavirus cases has risen steadily and has affected almost three-quarters of U.S. states. More than 1,000 cases and 31 deaths have been reported.

"Together we are putting into policy a plan to prevent, detect, treat and create a vaccine against CoronaVirus to save lives in America and the world. America will get it done!" President Donald Trump wrote on Twitter without giving more detail.

DISRUPTIONS TO DAILY LIFE

Daily life in the United States has been increasingly disrupted, with concerts and conferences canceled and universities telling students to stay home and take classes online.

Public gatherings have been suspended in a coronavirus "hot zone" in New Rochelle, a New York City suburb.

Democratic presidential contenders Joe Biden and Bernie Sanders were reassessing how to campaign in the face of the spreading outbreak.

The two candidates canceled rallies on Tuesday, citing recommendations from public health officials to avoid assembling large indoor crowds, and Biden's campaign scrapped a Thursday event in Florida, which holds a primary vote next week to help nominate a Democratic challenger to Trump in November.

The State Department has decided to suspend non-essential travel for its staff because of coronavirus, three sources familiar with the matter said.

The White House is examining payroll tax relief measures, loan guarantees, reimbursing workers for lost pay, aid to small and mid-sized businesses and support for airlines, hotels and other travel businesses, Mnuchin said.

"Whatever we do, kind of in the next 48 hours, that's just the first step. We'll be back. And I think there's big bipartisan support. People understand that we have to help small and medium-sized businesses and certain industries," Mnuchin told a House committee.

New York and Washington state are struggling to make testing for the virus widely available, with local officials estimating it could take weeks to reach peak testing capacity.

An unidentified flaw in test kits distributed by the federal government in February, which gave some false results, has set the country back in containing an outbreak that has infected more than 121,000 people worldwide.

(Additional reporting by Susan Heavey, David Lawder, Andrea Shalal, and Richard Cowan in Washington and Maria Caspani and Michael Erman in New York; Writing by Alistair Bell; Editing by Rosalba O'Brien, Lisa Shumaker and Cynthia Osterman)

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