The Senate is beginning to draft what likely will be the largest emergency relief and fiscal stimulus legislation in the country’s history – more than $1 trillion – to address the mushrooming coronavirus pandemic.

The heart of the emerging plan will be as much as $500 billion in rebate checks to individuals and households, likely means-tested to target the relief to middle-class Americans. The White House is pushing for checks to go out as soon as April 6, with a second check on May 18.

That package also is expected to include tens of billions of dollars in relief for the airline industry and other sectors, a loan program for small businesses, and more funding for state Medicaid expansion, unemployment benefits and paid sick leave.

It’s not clear when Congress will vote on this still-developing package. The Republican-controlled Senate is working through elements with the White House. Senate Majority Leader Mitch McConnell, R-Ky., will need Democrats’ support for any aid package, which would require 60 votes in the Senate.

House Speaker Nancy Pelosi, D-Calif.

The House is in a scheduled recess, but Speaker Nancy Pelosi, D-Calif., said lawmakers could return on 24 hours’ notice to vote on any new aid package. House lawmakers were scheduled to return next week, though staff expect they may return only to pass the stimulus before recessing again. (Two House lawmakers announced Wednesday they had tested positive for COVID-19, and many congressional offices have closed their Washington operations.)

President Donald Trump signed a multibillion-dollar aid package Wednesday that includes expanded family and medical leave policies, food assistance, and unemployment benefits. That law also guarantees free testing for COVID-19.

Trade groups representing restaurants, airports, hotels, manufacturers and other businesses also are weighing in with Congress and the White House to seek financial relief or changes in current laws.

But lawmakers on both sides of the aisle are reluctant to write a blank check. Congressional leaders in both parties want aid targeted to make it easier for businesses to retain workers even as the economy stalls – and to be positioned to rehire laid-off workers once the health crisis ends.

Sen. Elizabeth Warren, D-Mass.

But some in Congress want to go further than ensuring companies maintain their payrolls. Sen. Elizabeth Warren, D-Mass., wants any company that accepts federal relief to permanently prohibit share repurchases, install workers on boards of directors and require shareholder approval for political expenditures.

“Let me be clear: We’re not doing no-strings-attached bailouts that enrich shareholders or pay CEO bonuses,” Warren tweeted.

Sen. Sheldon Whitehouse, D-R.I., and seven other Democratic senators wrote to congressional leaders saying federal aid for the U.S. airline and cruise ship industries should include requirements to address pollution.

“Given the poor environmental records of some companies in these industries, we believe that any such financial assistance should be paired with requirements that companies act in a more responsible fashion,” the letter said.