The White House is taking a hard line with education authorities in its ambitious reform drive, ordering them to offer pupils at under-performing schools a place at better ones even if the latter are full.
Ratcheting up pressure on local schools chiefs, the US education department warned last week that overcrowding would no longer be an excuse. Authorities must forge deals with neighbours, hire extra teachers or build classrooms to accommodate pupils who transfer.
Officials were announcing the finishing touches to President George Bush's education reform, the "No child left behind" Act. This gives pupils the right to leave schools which have fallen short of state-based benchmarks more than two years in a row.
"We recognise that this is a considerable challenge and we are willing to work with state and local districts," said Eugene Hicock, under secretary of education. "But the idea that choice should be limited by a lack of capacity runs counter to the intent of this law."
Sounding an ominous warning to dissenters, Mr Hicock said: "Watch us. We are going to get pretty aggressive."
Since the Act was invoked in September, school choice has been granted to only a fraction of the eligible pupils. For example, of the 30,000-odd pupils entitled to switch in Baltimore only 176 were offered the opportunity. The picture is similar in many cities.
Moreover, of those offered the option, only a small minority have exercised it, amid parental confusion and a reluctance to send their children to distant schools.
Some have suggested that the White House's hard line is asking too much of cash-strapped education authorities and may even represent a backdoor route to private education vouchers, which could be the only way for many to comply with the edict.
Vouchers offering state pupils subsidies towards a private education are contentious because participating private schools are overwhelmingly religious.
School choice expert Patrick Wolf, assistant professor of public policy at Georgetown University, said both camps had a case. "It's a legitimate point that the (federal government) might be expecting too much too soon (but) this is intended to shake them out of a complacency that has been evident over time," he said.