THESE are austere times for government in America, with budgets shrinking for everything from the army to the National Zoo.

Republicans in Congress have taken every opportunity to enact new cuts, threatening shutdown and default if Democrats do not go along.

Many have also resisted the proposed immigration reforms working their way through the Senate, in part on the grounds that they would add to the government’s burdens by allowing newly admitted legions to sponge off Uncle Sam.

So it seems odd, to say the least, that the bill’s backers managed to secure more Republican support by agreeing to spend an extra $38 billion on it, largely by padding the government payroll.

As The Economist went to press, the Senate was poised to vote on the bill, which would overhaul America’s creaking immigration system, in part by allowing its 11m-odd illegal immigrants to stay, and after a long wait become citizens.

The bill’s approval seemed highly likely thanks to extra support garnered by Bob Corker and John Hoeven, Republican senators from Tennessee and North Dakota respectively. The original bill had proposed to increase spending on immigration enforcement by $8 billion; a Corker-Hoeven amendment inflates that to a spectacular $46 billion.

It requires the federal government to double both the number of border patrol agents, to 40,000, and the amount of fencing along the border, to 700 miles (1,100km). It also puts in place systems to identify those who have overstayed their visas and to ensure that no one hires any illegal immigrants. These measures must be implemented before most illegal immigrants can earn a permanent reprieve.

America’s border with Mexico is already bristling with motion detectors, floodlights, cameras and barricades of different sorts. The number of border patrol agents has doubled in the past decade. They are equipped with fleets of jeeps, boats, planes, helicopters and drones, not to mention sniffer dogs, night-vision goggles and the like.

The federal government spends $18 billion a year manning the ramparts, more than it does on the Federal Bureau of Investigation and the Drug Enforcement Administration put together. Yet academic studies suggest that other things, such as the state of the economy and the birth rate in Mexico, affect the flow of illegal immigrants far more than the sums spent trying to keep them out.

Small wonder, then, that Susan Collins, a Republican senator from Maine, denounced the Corker-Hoeven “border surge” as “excessive” and “wasteful”. Even Mr Corker has conceded that it is “almost overkill”. Yet Mrs Collins voted for it, as, naturally, did Mr Corker.

So did 13 more Republicans, giving it 67 of the Senate’s 100 votes. Some of those voting against, such as Rand Paul of Kentucky, complained not that it was too costly but that it was insufficiently tough (presumably because it does not include nuclear missiles).

Many among the Republican majority in the House of Representatives express similar misgivings. They argue that the border must be completely sealed—whatever that means—before any illegal immigrant wins even temporary leave to remain. John Boehner, the Speaker of the House, has said that he will not even put the Senate bill to a vote. Perhaps Messrs Corker and Hoeven were too stingy.