An immigration reform bill passed in the Senate last week would significantly reduce unauthorized traffic across the border and the number of people overstaying visas, according to a non-partisan government report released on Wednesday.
The net inflow of unauthorized immigrants could drop by anywhere from a third to half, according to a cost estimate of the legislation by the Congressional Budget Office (CBO).
That could be a much-cited figure as the bill's supporters look to sell it to skeptical Republicans in the House of Representatives.
The Senate legislation would double the number of Border Patrol agents, complete 700 miles of border fence, and invest billions in drones, sensors and helicopters.
The bill's sponsors agreed to add more spending on the border to woo Republican backers before last week's Senate vote, and to hypothetically give the legislation momentum in the House.
According to the CBO, the additional spending will be effective.
Before spending for the "border surge" was added to the legislation, it was only projected to cut the net inflow of unauthorized crossers by a quarter. The legislation as it stands now -- with $46.3 billion earmarked for border militarization -- could be twice as effective in cutting illegal immigration, the CBO found.
With a more secure southern border, the CBO estimates that the U.S. would add 9.6 million people over the first decade of the bill's hypothetical enactment. Originally, the budget office found the country would add 10.4 million over that period.