WASHINGTON – The Senate's top Republican and a handful of senior lawmakers in both parties are making a late-session push for legislation to create national standards for the horse racing industry to prevent fatalities and discourage illegal medication practices.Majority Leader Mitch McConnell, R-Ky., whose state is home to the country's top breeding outfits and the Kentucky Derby, introduced the legislation with senior Democrats from California and New York, which also have race tracks and breeding operations.The “Horseracing Integrity and Safety Act" comes after the racing industry has been hit by a series of doping scandals and a rash of fatal breakdowns in recent years.