Theres unlikely to be any formal paid sick leave in the latest COVID-19 rescue bill unless at least 10 Republicans sign on to it, despite the policys proven effectiveness in slowing the spread of the coronavirus, according to three congressional aides who spoke to HuffPost.

Without Republican support, Democrats will also likely have to leave out paid family and medical leave, illustrating the limitations of Democrats razor-thin majority in such a deeply partisan Congress.

Democratic aides said they didnt see a way to include a requirement that companies provide paid leave under the constraints of budget reconciliation, a legislative process Democrats are pursuing to pass legislation in the Senate with only a simple majority.

We knew a mandate would never survive [under Senate rules], said one Democratic House aide. Its not like we didnt expect it.

At best, the package would include tax credits for small businesses that opt to offer employees paid time off. A more substantive leave policy that passed with bipartisan support back in March 2020 did require some companies to provide paid leave. It expired at the end of last year.

It is what it is, said a Democratic Senate aide, who wasnt authorized to speak publicly about the state of negotiations. The aide said that it was still a good sign that tax credits will be included in the package, calling that momentum.

Though the details are still being worked out, the tax credits would likely be available only to small companies. These businesses would get some money back for giving workers paid time off to deal with COVID-19 issues. But its not clear if companies would even be required to let workers know such leave is available to them.

Most progressives dont see these tax breaks as anything close to legitimate paid sick leave, but simply an extension of the status quo. The U.S., unlike most other developed nations, does not mandate paid sick leave, so few companies offer it and typically only to fairly well-paid white collar workers.

Congresss failure to include paid sick leave during a pandemic has frustrated progressive advocates. Paid sick and family leave is needed for a raft of critical reasons: First, it would allow workers exposed to COVID-19 to stay home to quarantine or recover from their illness, thus preventing the spread of the disease. The leave could also give workers time off to go get vaccinated. And longer-term family leave is critical to parents who need to be home with children because of school and day care closures. Already millions of women were pushed out of the labor force to deal with that pressure.

The rescue package floated by 10 Republican senators last week, countering Bidens opening proposal, entirely omitted the policy.

Advocates call it a wasted opportunity.

It remains deeply disappointing and utterly incomprehensible that Democrats and Republicans cant come together around a public health policy that would prevent COVID cases, help the vaccination process and help keep people in the workforce, said Vicki Shabo, a paid-leave specialist at the New America think tank. Especially women and people of color.

With 50 seats in the Senate, and Vice President Kamala Harris as the tie-breaking vote, Democrats can pass their relief bill without any Republican support through budget reconciliation a process they started this week. Otherwise, any bill passed by the Senate needs 60 votes to overcome a filibuster.

But while bypassing Republicans means Democrats can get a lot of things their colleagues across the aisle have balked at, reconciliation comes with some tradeoffs.

Reconciliation bills must directly impact federal spending or revenue, and they also cannot raise the deficit beyond a certain threshold over the next 10 years. In this case, Senate Democrats put that top-line figure at $1.9 trillion.

A blanket paid leave requirement, or mandate, doesnt directly impact the budget, and therefore would run afoul of Senate rules. Democrats havent yet decided whether they will include the mandate in their final bill text and simply subject it to an objection from a Republican colleague on the Senate floor.

There are some workarounds. Democrats are pursuing one in this emergency relief push, structuring a paid-leave tax credit for some businesses similar to one that passed back in December.

In the event the mandate cant survive through reconciliation, Democrats are budgeting to continue the voluntary credits from the December deal, a Democratic aide familiar with the talks said.

But without requiring companies to actually give employees paid time off, these tax credits just dont amount to much.

Last year, Congress did have bipartisan momentum around leave, and was able to mandate that some businesses offer paid sick leave to deal with the coronavirus.