Los Angeles hopes to woo the world in 2028 when millions of people pour into the second-largest U.S. metro region to attend the Olympic Games, but it faces an uphill battle to reach its goal of becoming a zero-emissions transportation city by then.

In 2018, the city launched a 10-year plan to make the region’s cars, buses, and trucks emissions-free by the 2028 Summer Olympics and is now more than halfway to the finish date, but officials involved admitted to attendees at the South by Southwest Conference on Tuesday afternoon in Austin that they have much to do.