Asked in an interview with German public radio Bayerischer Rundfunk about speculation he would succeed Rumsfeld at the Pentagon if Bush won the vote Tuesday, Ambassador Daniel Coats replied: "First I will wait to see what happens in the election and then I will do what best serves my country.
"I have a long-standing interest and experience in defense issues and foreign policy," he said according to a German transcript of the interview.
"If the opportunity arose to contribute in this area and the president asked me then I would seriously consider it."
A US embassy spokeswoman confirmed Coats' comments.
The former Republican senator from Indiana had been among the front-runners for the Pentagon job when Bush was elected in 2000.
In May, amid pressure on Rumsfeld to resign in the wake of the Abu Ghraib prisoner abuse scandal in Iraq, German news weekly Focus reported that US National Security Advisor Condoleezza Rice had approached Coats about the Pentagon job on a visit to Berlin that month.
Coats, who became Washington's envoy to Germany in September 2001, reportedly told her he would be interested.
A US embassy spokesman declined to comment on the report at the time, saying only: "We expect him to be here in Berlin at least until the election in November."