WASHINGTON — Treasury Secretary Janet Yellen warned of "tough months ahead" with COVID-19 continuing to flare, making it critical that Congress pass President Joe Biden's $1.9 trillion relief package.

In her first public interview since becoming Treasury secretary last week, Yellen said that Biden is willing to cooperate with Republicans to pass the measure on a bipartisan basis.

Democrats in Congress have signaled, however, that if GOP support is not forthcoming, they are prepared to pass the measure with only Democratic support.

On Wednesday, the House passed on a nearly party-line vote a budget bill that would allow special rules to be used in the Senate to pass the relief bill by a simple majority rather than the 60 votes needed for most bills in the Senate.

"This is really an urgent need and we need to act big," Yellen said Thursday on ABC's "Good Morning America. "We've got some tough months ahead" until we get control of the pandemic.

 Asked how it feels to be the first woman to serve as Treasury secretary, Yellen, was also the first woman to lead the Federal Reserve, said that the legacy she seeks is in the passage of a coronavirus relief measure. 

America faces "an economic crisis that is as serious as I have seen in my lifetime," Yellen said. The goal, she said, is to ensure that "Americans don't suffer needlessly."

Contributing to the passage of a relief bill, which she said by some estimates could reduce childhood poverty by 50%, would be "a great legacy for me."

Yellen also spoke about recent stock market trading turmoil that pitted smaller, online investors against massive hedge funds. That fight, led by a band of traders on Reddit, have sent shares of severely damaged companies like GameStop and AMC soaring. 

Yellen said she is meeting later Thursday with federal regulators from the Securities and Exchange Commission, the Federal Reserve and the Commodity Futures Trading Commission.

"We really need to make sure that our financial markets are functioning properly and efficiently and that investors are protected," she said. 

The meeting will be focused on what happened and whether any regulatory action is warranted.