WASHINGTON —A congressional effort to delay upcoming flood insurance rate increases for many thousands of Louisiana residents, and others nationwide, was defeated Tuesday by a single senator who threatened to bring this week’s U.S. Senate floor action to a screeching halt.

The proposal — by Sen. Mary Landrieu, D-La., with the backing of Sen. David Vitter, R-La. — was an amendment to Vitter’s water resources infrastructure bill. The amendment would have stalled premium increases of 20 percent or more annually for some residents in the National Flood Insurance Program.

But Sen. Pat Toomey, R-Pa., used a procedural move to block all the proposed amendments to the bill from receiving votes, unless Landrieu withdrew her proposal. She did in order to avoid gridlock.

Toomey objected to the “unanimous consent” request to move to the amendment votes.

Landrieu said afterward that she will file a standalone flood insurance bill that she will push to move quickly.

Toomey argued that he does not want to continue the “unfair subsidy” paid by the federal government to homeowners living in risky areas. “We put in place a mechanism to diminish the subsidization we have now,” Toomey said, arguing in support of the flood insurance authorization approved last year.

Landrieu’s amendment creates a “moral hazard of a risk” to continue building in high-risk areas,” Toomey said.

Landrieu said the flood insurance authorization was tucked into a larger omnibus bill last year and was never properly tweaked and amended to protect working-class residents who live along coastal areas.

“He (Toomey) is just saying we can’t even have a vote,” Landrieu said. “This is going to come back to haunt him because the people of his own state are going to be negatively affected.”

Landrieu said legislation is needed to ensure the flood insurance is both affordable and sustainable. “This is big government at its worst — passing a reform bill and making the cure worse than the disease,” Landrieu said.

Vitter also complained to Toomey, arguing that no senator “should object to having just a vote on the matter.

“We will revisit this issue because it is vitally important we get it right,” Vitter said.

A final vote on Vitter’s Water Resources Development Act is expected Wednesday. The bill is intended to expedite U.S. Army Corps of Engineers processes, set aside more dollars for river dredging and speed up flood-protection projects like southern Louisiana’s Morganza to the Gulf plan in Terrebonne Parish.

But the legislation will not address the NFIP.

The insurance fear is that proposed flood maps will cost Louisiana residents and business owners a lot more in the congressional effort to make the flood insurance program more self-sustainable. The proposed flood maps are still under federal review but more parts of the state’s coast are becoming high-risk velocity zones, or V-zones, where insurance rates increase more. The program also is going to start phasing out “grandfathered” rates next year.

The NFIP allows homeowners and businesses in flood zones that have trouble getting private insurance to obtain policies backed by the federal government.

Nearly 500,000 people in Louisiana participate in the NFIP. The program has been in financial distress with a loss of more than $20 billion, largely due to payments made after hurricanes Katrina and Rita in 2005.

The Federal Emergency Management Agency estimated that more than 400,000 of those in the program in Louisiana would not face immediate impacts, although they are subject to annual rate increases. Another 50,000 properties will maintain the present rates or “grandfathered subsidies” until they are sold.

Louisiana officials have argued that more people will face “skyrocketing” rate hikes than FEMA suggested.

Landrieu argued that many working-class coastal residents will no longer be able to afford flood insurance and have to move. But their homes will become “unsellable” because no one else will be able to take on the flood insurance rates.