WASHINGTON - A chorus of opponents has accused the Obama administration of overstepping its legal authority with a proposal to regulate the spending of billions of dollars meant to help educate children from poor families.

The nonpartisan Congressional Research Service bolstered that criticism, finding in May that the proposed regulation appeared to "go beyond what would be required by a plain reading of the statute."

But a new analysis - conducted by attorneys at WilmerHale at the request of the Leadership Conference on Civil and Human Rights and provided to The Washington Post - comes to a different conclusion, finding that the Education Department has "ample" legal authority to move forward with its proposal.

The dueling legal opinions are just one sign of what has become one of the most fiercely contested national issues in education. Though it receives far less attention than the Common Core State Standards, testing or charter schools, the Education Department's proposal has the potential to dramatically reshape how school districts nationwide allocate money and teachers among campuses.

Federal law has long said that school districts cannot underfund schools in poor neighborhoods and then use federal Title I dollars to fill the hole. Instead, they must ensure that schools in poor neighborhoods get all the state and local dollars they would if Title I dollars were not available - an attempt to give children from poor families a fairer shot at a decent education.

Nevertheless, many Title I schools continue to receive fewer dollars than more-affluent schools in the same district. And the requirements for showing compliance with the law were almost universally regarded as onerous and often counterproductive to providing students with the services they needed.

Congress attempted to solve that in the new Every Student Succeeds Act, which passed last year, by maintaining the spirit of the provision but tweaking its language. Now, school districts must show that the methodology they use for allocating state and local money to schools is fair and does not shortchange schools in poor neighborhoods.

The controversy centers on a regulation that the Education Department has proposed to implement that law. It has undergone several iterations and has yet to be finalized. But at its heart is the notion that school districts must show they are spending a roughly equivalent number of state and local dollars per pupil in high-poverty schools as in more-affluent schools.

Critics - including one of the lead authors of the law - say that Congress never intended to require school districts to meet such a test and that the Education Department is using regulations to unilaterally rewrite the law.

"It is unfortunate that, once again, the Department has refused to adhere to the letter and intent of the law," Sen. Lamar Alexander, R-Tenn., chairman of the Senate Health, Education, Labor and Pensions Committee, and 24 other GOP Senate and House members wrote to Education Secretary John King Jr. on Friday.

The funding provision, they wrote in an eight-page letter, "has never required, nor is it intended to require, equity or fairness in the allocation of state and local education dollars."

The Education Department says its proposed regulation would serve to fulfill the civil rights intent of the law, which was initially passed in 1965 as part of President Lyndon B. Johnson's War on Poverty. And the legal analysis from the Leadership Conference on Civil and Human Rights argues that the law is ambiguous and that the Obama administration is offering a reasonable clarification of its meaning.

Liz King, education policy director for the Leadership Conference, said the organization plans to make its analysis public Monday and hopes to bring an end to the debate about whether the Education Department's approach is legal and create more space for debate over the substance of the policy.

There is great disagreement about whether the Education Department's approach would improve conditions for disadvantaged children, as intended, or whether it would create new obstacles for schools by introducing chaos into the way districts fund their operations.

Teachers unions, state education chiefs, local superintendents and school boards have voiced opposition, saying that though well-meaning, the proposal is unworkable in real life.

Because most districts' budgets are tied up in personnel costs, and most communities do not have surplus dollars to put into high-poverty schools, the only way to equalize spending would be to force higher-paid teachers to transfer to high-poverty schools, they say. They say that the proposal is grounded in the wrongheaded assumption that higher-paid teachers are more effective, that it would probably violate collective-bargaining agreements, and that it would give principals less say in which teachers to hire.

They also have said that the department's proposal could bring an end to specialized programs such as magnet, bilingual or International Baccalaureate schools, since demonstrating compliance would be easier for districts that offer the same programs in each school.

"We believe that the regulation, as drafted, glosses over the realities of school finance and reduces the intricate nuances of equitable funding to 'robbing Peter to pay Paul,' " the heads of all 50 states' associations of superintendents wrote in a letter to the department.

Democrats Sen. Patty Murray, Wash., and Rep. Robert "Bobby" Scott, Va., who have supported the thrust of the department's regulation, also cautioned that the proposal needs tweaking. It calls on districts to send "almost all" of their money to schools, a vague reference that seems to ignore how districts pay for transportation or preschool.

The department has received more than 3,000 public comments on its proposal. The comment period closes Monday, and the agency is seeking to finalize the rule before President Barack Obama leaves office in January.