The Prevention of Equine Cruelty Act, if passed into law, would ban slaughter in the US and prevent the current export of more than 86,000 horses a year to slaughter plants in Canada and Mexico.
No plants currently operate in the United States after the forced closure of three under state laws.
"Every day that passes means that there will be more torment and more suffering for America's horses," said Wayne Pacelle, president and chief executive of the HSUS.
"The horse is an American icon, and it is a betrayal of our responsibility to these animals to treat them like cheap commodities and send them across our borders for slaughter.
"We ask leaders in Congress for an up or down vote and passage of this critical legislation."
A bipartisan coalition of lawmakers introduced the legislation this week.
House Judiciary Committee chairman John Conyers (D-Mich.) and Dan Burton (R-Ind.) introduced the bill, known as the Conyers-Burton Prevention of Equine Cruelty Act.
Its passage is a top priority for the HSUS.
Conyers and Burton were joined by 59 original co-sponsors in introducing the bill, which failed to make it through the last Congress.
State lawmakers have acted to stop horse slaughter, shuttering the last remaining foreign-owned horse slaughter plants in the US in 2007, and federal courts have upheld those state laws.
But the HSUS says Congress has failed to act to stop the export of live horses to Canada and Mexico for slaughter.
More than 86,000 horses were sent across US borders to slaughter in Canada or Mexico in 2008.
Past congressional actions on horse slaughter have demonstrated a strong desire, across party lines, to prohibit killing horses for human consumption.
In the 109th Congress, legislation to stop horse slaughter passed the House of Representatives numerous times by a margin of more than 100 votes, and passed the Senate by a more than two-to-one margin.
But in the 110th Congress, prior legislation was not enacted because it was blocked by House committee leaders and Western senators.
Animal advocates hope the new bill will advance quickly in Chairman Conyers' House Judiciary Committee.
The HSUS is joined by members of Congress, the National Show Horse Registry, American Horse Defense Fund, Veterinarians for Equine Welfare, United States Equine Sanctuary and Rescue, and more than 500 endorsing organisations, along with a majority of Americans (according to surveys) in support of the Conyers-Burton Prevention of Equine Cruelty Act.
* September 2008 - House Judiciary Committee passes HR 6598 by voice vote after majority reject multiple poison pill amendments.
* July 2008 - Chairman John Conyers and Dan Burton introduce HR 6598, legislation amending Title 18 to prohibit horse slaughter for human consumption as a form of equine cruelty.
* September 2007 - A three-judge panel from the US Court of Appeals for the Seventh Circuit unanimously upholds the Illinois state law banning the slaughter of horses for human consumption in that state.
* May 2007 - Governor Rod Blagojevich signs HB 1711, banning horse slaughter in Illinois.
* May 2007 - The US Supreme Court announces that it denies to consider an appeal of the lower court decision upholding Texas' ban on the sale of horsemeat for human consumption.
* April 2007 - US House of Representatives passes HR 249 to restore a decades-old ban on the commercial sale and slaughter of wild horses first enacted under the Wild and Free-Roaming Horses and Burros Act of 1971. House vote: 277-137
* April 2007 - US Senate Commerce Committee votes 15-7 to approve S 311 to ban horse slaughter and exports of horses for slaughter.
* March 2007 - A federal district court orders the US Department of Agriculture to stop inspecting horsemeat at the Cavel International slaughter plant, effectively closing the last operating horse slaughtering operation in the United States.
* March 2007 - The United States Court of Appeals for the Fifth Circuit affirms decision upholding a Texas state law banning the sale of horsemeat for human consumption.
* September 2006 - US House of Representatives passes HR 503, the American Horse Slaughter Prevention Act. The 109th Congress adjourns before the Senate can consider the bill. House vote: 263-146
* September 2005 - US Senate approves the Ensign-Byrd Amendment to the FY 2006 Agriculture Appropriations Bill to prohibit the use of tax dollars to pay for inspections of horsemeat. Senate vote: 69-28
* June 2005 - US House of Representatives approves the Sweeney-Spratt-Rahall-Whitfield Amendment to the FY 2006 Agriculture Appropriations Bill to prohibit the use of tax dollars to pay for inspections of horsemeat. House vote: 269-158
* May 2005 - US House of Representatives approves the Rahall-Whitfield Amendment to the FY 2006 Interior Appropriations Bill to restore federal protections from commercial sale and slaughter to wild horses and burros. House vote: 249-159. The provision is stripped in conference from the final bill.