The bill, the "Fairness for High-Skilled Immigrants Act" (H.R. 3012), which sailed through the U.S. House late last month on a 389-to-15 vote, eliminated per-country caps on employment-sponsored green cards.

But Grassley, who has been fighting for major changes in the H-1B rules, didn't specify what changes he is seeking to the House bill. It's possible that he may be using the legislation to seek broader concessions in the use of all employer-sponsored visas, including H-1B.

Grassley, the ranking Republican on the Senate Judiciary Committee, last week placed a "hold" on the bill, putting it in a procedural limbo that may sink this effort.

"I have concerns about the impact of this bill on future immigration flows, and am concerned that it does nothing to better protect Americans at home who seek high-skilled jobs during this time of record high unemployment," said Grassley, last week, in the Senate in announcing his action.

The House bill doesn't increase green-card immigration, but is designed to reduce the wait for permanent residency where the backlog for green cards is the longest, particularly in India and China. The U.S. issues 140,000 employment-sponsored green cards annually under a system that sets uniform per-country caps.

But Grassley's comment about the bill and his reference to worker protections suggest that he is seeking a broader bill.

Grassley, along with Sen. Dick Durban (D-Ill.), has been trying for years to reform the H-1B visa program to give U.S. workers preference in hiring, increase the prevailing wages, and limit use of the visa by offshore outsourcing firms.

Sen. Mike Lee (R-Utah) introduced a companion bill (S. 1857) to the House bill.