With just two days before the National Flood Insurance Program is set to expire, the most recent six-month hand-wringing cycle has come to a head. Congress has until midnight Friday to extend the federal program and avoid a lapse that could complicate many flood insurance policies and new home sales.

The federal flood program is the primary way homeowners buy flood insurance. Florida makes up about 40 percent of its policies, while Pinellas County has the largest number of properties that receive subsidized rates under it. Depending on where a home is located, flood insurance can be a mandatory requirement of a mortgage.

Lawmakers, policy holders and their advocates have for years called for changes to the program, citing a complicated sign-up and appeals process, a growing deficit and the inability of homeowners to move between the federal program and the private market. Many want at least a five-year reauthorization with improvements in these areas instead of the spate of short-term extensions.

As Friday’s deadline approaches, there are three possible scenarios that could take place: Congress renews the program for six months, Congress renews the program for seven days or the program lapses.

“Right now the center of gravity is in the Senate,” said Nat Wienecke, senior vice president for government relations at the Property Casualty Insurers Association of America.

That’s because the Senate, Wienecke said, is the body that needs to push the temporary reauthorization through. A six-month extension would provide the most relief, pushing the next deadline off until the end of May 2019. Lawmakers would then have another buffer to find a longer-term solution. Last year, the House passed a bill aimed at providing a long-term fix, but the Senate has not introduced its own version.

The next possibility is a seven-day extension bill proposed by the House. But that would push the decision into the same time frame as the government spending bill deadline of Dec. 7 amid fears of a government shutdown.

Should no extension be reached before the end of Friday, the most dire scenario would play out – a lapse. In that case, homeowners who are trying to close on a new home or refinancing their current home will not be able to get a new flood insurance policy, said Steve Ellis, executive vice president at budget watchdog Taxpayers for Common Sense.

Because the deadline backs up to a weekend, Ellis said, a one- or two-day lapse may not affect this group significantly, as most home sales and insurance policies are not written on the weekends.

Homeowners who have flood insurance policies purchased before Nov. 30 will not be affected. Patty Latshaw, principal flood coordinator for Wright National Flood Insurance, said homeowners who may be affected should file their flood insurance applications before the deadline.

The Federal Emergency Management Agency, however, is confident some form of an extension will be passed.

“FEMA is confident Congress will vote to reauthorize this program so individuals, families, businesses and communities can purchase insurance to protect their homes and businesses from flooding,” the agency said in a release last week.

Contact Malena Carollo at mcarollo@tampabay.com or (727) 892-2249. Follow @malenacarollo.