Why would Sunday's election in a poor country of nine million people leave Washington fretting?
Despite its obscurity for many Americans, Bolivia has one of the largest US embassies in Latin America. The main reason for that is coca - the key ingredient in cocaine.
The US has spent billions of dollars eradicating coca plants and promoting alternative crops. But presidential front-runner Evo Morales wants to decriminalize Bolivia's native plant.
Another major concern, say US officials, is the relationship between Mr. Morales and Venezuela's Hugo Chávez. "The administration has found mounting evidence that Venezuela is actively using its oil wealth to destabilize its democratic neighbors in the Americas by funding anti-democratic groups in Bolivia, Ecuador, and elsewhere," wrote acting Assistant Secretary of State Matt Reynolds earlier this year.
No evidence supporting those claims has been presented. But Morales supporters have taken to the streets to help bring down two presidents in just over two years, raising concerns about his commitment to ballot-box democracy.
Even if Mr. Chávez isn't giving Morales financial support, there is little doubt about his rhetorical support. Morales says he has learned much from Chávez's approach to the oil industry. Last May, his party backed a law that more than doubled taxes on foreign-owned oil companies.
With nearly a dozen elections in Latin America over the next year, including Brazil, Mexico, and Ecuador, the US doesn't want Chavez's or Morales's influence to spread. But analysts say much will depend on how Morales and the US react.
"The US should initially seek to have a reasonable relationship with the new government," says Mark Schneider of the Crisis Group in Washington, DC. "There is a big difference between campaign statements and government policy."