Lawmakers in the House of Representatives and the Senate have until Friday at midnight to reach a funding agreement in order to avoid a shutdown. Republicans and Democrats will have to agree on a number to fund the federal government that will go through September 2023, the end of the fiscal year.

While speaking with NBC News on Sunday, Senator Richard Shelby, an Alabama Republican, who serves as the vice chairman of the Senate Appropriations Committee, said Republicans and Democrats have not yet reached an agreement for the omnibus federal government spending package and are approximately $26 billion apart on domestic spending. The spending package would likely be more than $1.5 trillion, according to the news organization.

“We haven’t reached an agreement, we’re not near an agreement, but the circumstances are there…that we could reach one,” the senator added.

In a statement on Monday, a spokesperson for the United States Postal Service (USPS) told Newsweek, “Postal Service operations will not be interrupted in the event of a government shutdown, and all Post Offices will remain open for business as usual. Because we are an independent entity that is generally funded through the sale of our products and services, and not by tax dollars, our services will not be impacted by a government shutdown.”

During another government shutdown in 2013, the USPS issued a similar statement on Facebook and said, “Despite the Federal government shutdown, all U.S. Post Offices™ will remain open and mail delivery services are running as normal.”

However, the USPS Office of the Inspector General (OIG) will be “affected” in the case of a shutdown.

As lawmakers on both sides of the aisle work to come to a funding agreement, CNN reported on Monday that the White House Office of Management and Budget (OMB) recently released guidance for federal agencies in the event of a shutdown.

“One week prior to the expiration of appropriations bills, regardless of whether the enactment of appropriations appears imminent, OMB will communicate with agency senior officials to remind agencies of their responsibilities to review and update orderly shutdown plans, and will share a draft communication template to notify employees of the status of appropriations,” the OMB said in a document, according to CNN.