If a little-known but influential alliance of state politicians, large retailers, and tax collectors have their way, the days of tax-free Internet shopping may be nearly over.

A bill expected to be introduced in the U.S. Congress as early as Monday would rewrite the ground rules for mail order and Internet sales by eliminating what its supporters view as a “loophole” that, in many cases, allows Americans to shop over the Internet without paying sales taxes.

“One of the big things the states have learned in the recession is they have declining revenues,” said Scott Peterson, executive director of the Streamlined Sales Tax Project, which counts state politicians and tax collectors on its governing board. “We’re very optimistic about Congress this year. We think we are within a day or two of finalizing the legislation.”

The final legislation is expected to be introduced by Sen. Mike Enzi, a Wyoming Republican, and Rep. Bill Delahunt, a Massachusetts Democrat, who have championed similar proposals in the past. Delahunt’s office on Wednesday confirmed he was interested; Enzi’s did not respond.

Take aim at foot, pull back hammer, fire.