April 24: This post has been updated to include the response from the Westchester Count Executive Rob Astorino.

The showdown in Westchester County over a 4-year-old federal residential desegregation order just got real.

The U.S. Department of Justice sent a letter to the New York City suburb last Friday threatening to seek a contempt ruling in federal court. A contempt ruling could result in fines against both the county and County Executive Rob Astorino if he fails to agree to enact legislation that would ban discrimination against people who pay their rent with government assistance.

Westchester County signed a settlement with the federal government in 2009 over its failure to comply with fair housing requirements tied to federal grants. The settlement required Astorino to promote legislation — known as source-of-income measures — that would end discrimination against those using government subsidies to help pay their rents. Instead, Astorino vetoed the law passed by the county's Board of Legislators in 2010 that would have addressed the issue.

Astorino — who campaigned for office on his opposition to the settlement — went to court to challenge the government's contention that his actions had in fact violated the court order. He lost in that bid earlier this month. And on April 5, a federal appeals court upheld the district court's ruling that Astorino’s action breached the settlement and ordered him to promote and sign the legislation.

"The County would have this Court rely upon the legitimate concerns that motivate modification of long-standing consent decrees to allow the County to shirk its voluntarily agreed to obligations, made less than four years ago, with no showing that the objects of the consent decree have been obtained and strong evidence indicating that they have not been," the court ruled. "This we will not do."

The Justice Department gave Astorino until Thursday to agree to comply and appears willing to head to court if he doesn't. In the letter sent to the county last Friday, the Department of Justice said that it could first seek contempt fines against the county. If those proved fruitless, it could seek fines against the county chief himself.

Earlier this month, the U.S. Department of Housing and Urban Development notified the county that it would permanently lose $7.4 million in federal grants if it did not produce a detailed plan to comply with three major requirements of the 2009 settlement, including the income discrimination ban and producing a plan to attack exclusionary zoning in the county's whitest municipalities.

HUD also gave the county until Thursday to comply. The stripping of these grant dollars would be unprecedented.

Combined, this month's efforts mark the federal government's most aggressive steps to date to compel compliance with what was considered a landmark fair housing settlement. A ProPublica investigation published late last year detailed the reluctance on the part of federal officials to press county officials too hard to meet the terms of the settlement, even when those county officials were openly defiant of the settlement's goals and mandates.

But Craig Gurian, who runs the nonprofit Anti-Discrimination Center that brought the lawsuit against Westchester leading to the settlement, remains skeptical of the government's determination. He noted that the U.S. Attorney threatened to hold Westchester in contempt last year over the income discrimination ban but backed off when the county gave assurances it would comply.

"The U.S. Attorney's promised action is welcome, but we remain concerned about the willingness of that office and of the Obama administration in general to vindicate fully the promise of the consent decree," he said. "The U.S. Attorney continues to ignore the fact that Westchester has been violating every material obligation of the consent decree for three-and-a-half years. The proper course is to seek to hold Westchester in contempt for all of its violations; it is not acceptable to allow civil rights defendants to fail to obey any element of a court order."

So far, the federal government's threats have not prodded the county to change course. Astorino accused HUD of extortion and last week the Board of Legislators voted to support Astorino's request to sue HUD over the imperiled grant money.

Astorino's office did not respond to a request for a comment. But County Chairman Kenneth Jenkins, a harsh critic of Astorino's handling of the settlement, released a statement today imploring Astorino to act. Jenkins, along with three other Democrats, voted against the county suing HUD. He said Astorino, a Republican, should deliver the legislation to the board by the end the day.

"I have been asking County Executive Astorino, both privately and publicly, to comply with the fair and affordable housing settlement, especially in regard to submitting Source of Income Legislation to the Board," Jenkins said. "Obviously, the hammer is coming down."

Jenkins knows how that hammer can work, and hurt. Jenkins once headed the Yonkers chapter of the NAACP, which had sued the Westchester County city of Yonkers over segregation in its schools and neighborhoods. Elected officials, in a long and brutal battle, nearly bankrupted the city when their efforts to resist a federal residential and school desegregation order led to massive fines.

Update (April 23): Westchester County Attorney Robert Meehan responded this afternoon to Friday’s letter from the U.S. Attorney's Office. Read the letter here.

Update (April 24): Westchester County Executive Rob Astorino submitted legislation today to ban discrimination against people who pay their rent with government assistance, a day after the U.S. Department of Justice threatened to haul the county into court over the issue.

In a letter to the county’s Board of Legislators, Astorino wrote, "In light of all of the foregoing, I recommend the adoption of this proposed Local Law."

It is a marked change in tone from the letter County Attorney Robert Meehan sent the U.S. Attorney's Office for the Southern District of New York yesterday. In that letter, Meehan called the Justice Department's contentions about noncompliance with a court order to promote and pass the legislation "wholly without merit and simply argumentative."

County Chairman Kenneth Jenkins released a conciliatory statement this afternoon.

"County Executive Astorino has forwarded the Source of Income legislation to the Board as demanded by the Department of Justice to avoid contempt of court and crippling fines against the County," the statement said. "It is time for the Administration to work through the necessary requirements of the housing settlement without all of the overheated political rhetoric — for the sake of all of our residents and taxpayers."