Opponents of the Senate immigration reform bill have held as an article of faith that citizenship for those who have entered the country illegally will create huge costs by making those people eligible for government benefits.

A new analysis by the nonpartisan Congressional Budget Office turns that notion on its head and should serve as a powerful inducement to approve the Senate bill.

In the first decade after passage, the CBO estimated, the gradual addition of millions of new taxpayers would decrease the federal deficit by $197 billion.

Opponents contend that the true costs would come in the following decade, when all of the immigrants subject to the bill would have legal residence status and be eligible for benefits.

The CBO finding was stunning. It said that, in the decade from 2024 through 2033, deficit reduction due to the bill would total $700 billion.

And the analysis does not consider the impact on local tax revenue.

According to the CBO, the bill would lead to a net increase of 10.4 million permanent legal residents and 1.6 million temporary workers and their dependents, and a decrease of 1.6 million unauthorized workers.

Unfortunately, the bill has poor prospects in the House even it passes the Senate, despite its merits for individuals and the national good. Speaker John Boehner said last week that he will not move the bill for a vote unless it has the support of a majority of the Republican Caucus.

That is not governance. The House Republican Caucus is 53 percent of half of one branch of the federal government. Confining votes to only what a majority of any particular caucus deems palatable insults basic representative democracy. Mr. Boehner should ensure that the immigration bill gets not only a debate, but a vote.