First Lady Michelle Obama and Jill Biden received a mixed welcome to NASCAR’s season-ending Ford 400 Sunday, where they served as grand marshals to help raise awareness for their “Joining Forces” initiative, which supports military families.

Winning time
NASCAR action heats up in the championship-determining weekend. Photos.Scattered boos could be heard from the crowd as Obama and Biden were introduced and invited to give the traditional command, “Gentlemen, start your engines.”

Scattered boos could be heard from the crowd as Obama and Biden were introduced and invited to give the traditional command, “Gentlemen, start your engines.”

Earlier, Obama and Biden had addressed the drivers’ meeting at Homestead-Miami Speedway, the Sun Sentinel reported.