Senate Democrats have beaten back an ambitious, industry-supported amendment to the derivatives portion of financial reform legislation.

If passed it would have significantly weakened the administration’s efforts to tighten regulation of over the counter derivatives markets.

Yesterday’s vote went largely along party the lines (39-59). But Senate Democrats attracted support from moderate Republicans Olympia Snowe (Maine) and Charles Grassley (Iowa), making that part of the bill effectively filibuster proof.

So far lobbyists have largely failed to change the direction of the bill despite heavy pressure on members of the chamber to make it more industry-friendly.

It now looks like the final derivatives reform will be largely along the lines advocated by the White House and the U.S. Treasury Department, and that industry lobbying will not materially affect the outcome.