Early Saturday morning — as concerns about the coronavirus outbreak continued to grow — the House passed a massive bill guaranteeing free coronavirus testing to all Americans.

The Senate, meanwhile, was nowhere to be found.

In fact, many lawmakers including Senate Majority Leader Mitch McConnell had already left for the weekend. Senate leadership, rather than sticking around, opted to return next week, prompting an apparent delay in their consideration of this legislation as states and medical providers grapple with an influx of coronavirus cases.

The House still needs to make some adjustments to the bill, however, according to Treasury Secretary Steven Mnuchin. During a press conference on Saturday, Mnuchin said the House needed to make some “technical corrections” to the bill, which could mean that lawmakers will have take another vote on Monday. Doug Andres, a spokesman for McConnell said as much on Saturday, and argued that the attacks on the Senate were unwarranted.

It’s worth noting that the House has not finished their work. Mnuchin just announced the House needs to pass a correction to the package on Monday. The Senate has no bill to vote on. https://t.co/t114JQ5vgU — Doug Andres (@DougAndres) March 14, 2020

McConnell’s decision to leave the Capitol had spurred extensive criticism from Senate Democrats, who’ve called his decision “irresponsible” and “out of touch.” McConnell on Thursday canceled the Senate recess originally scheduled for next week, but opted to travel back to Kentucky as the House was still working on its deal with Mnuchin.

The Senate majority leader’s move to distance himself from the negotiation process and go home has led to the hashtag #WheresMitch, which first emerged during the government shutdown last year, to trend on Twitter.

Given Trump’s support, the legislation — called the Families First Coronavirus Response Act — is poised to pass the Senate next week. In addition to free testing, it includes 14 paid sick days for workers during the coronavirus outbreak, as well as paid leave that people will be able to use for up to three months.

McConnell has been skeptical of aspects of the measure in the past, and the upper chamber’s response won’t be fully evident until they return to vote Monday evening. He did, however, signal that lawmakers would consider it quickly via a statement Saturday morning.

“Senators will need to carefully review the version just passed by the House,” he said. “But I believe the vast majority of senators in both parties will agree we should act swiftly to secure relief for American workers, families, and small businesses.”

Why there’s so much urgency

A two-day delay does not seem like much in the grand scheme of things, but the fluidity of the coronavirus situation has led to McConnell’s critics, like Senate Minority Leader Chuck Schumer, arguing that it’s too long to wait. The House, it seems, has played a role in this delay as well.

It’s one that has serious implications. For example, there were 938 confirmed cases in the US as of the morning of March 11; two days later, on the morning of March 13, there were 1,215. In the last few days, President Trump has also declared a national emergency intended to unlock more funding for states to use as they combat the outbreak.

And as Vox’s Eliza Barclay and Dylan Scott have written, there’s still a lot we don’t know about how quickly the coronavirus could spread. Depending on how many people contract the virus, a number that could range in the thousands soon, hospitals are set to be overwhelmed with cases and in need of more resources for testing and treatment.

This makes the relief included in the bill — particularly the free testing — of utmost importance.

Thus far, there’s been a striking shortage of coronavirus tests that doctors and patients are even able to access. As of the early hours of March 14, just over 19,000 tests had been conducted in the US, according to the COVID Tracking Project. That figure pales in comparison to some other countries that are dealing with coronavirus crises including South Korea, which has tested more than 140,000 people.

As Vox’s Brian Resnick and Dylan Scott write, testing can be imperative both in identifying patients who have the virus, and in tracking others they may have been in contact with, to contain its spread. The United States’ systemic failure to test more individuals so far has likely kneecapped its ability to more effectively reduce the virus’s reach.

Free testing also makes it more likely that individuals who need it will attempt to get one. As Rep. Katie Porter pointed out in a hearing last week, the total out-of-pocket costs of a coronavirus test could wind up being more than a thousand dollars.

As a result, the legislation that Congress is considering is incredibly critical — and could have a pivotal impact in addressing the effects of the coronavirus.