Is 'The Star-Spangled Banner' racist?

When we sing "The Star-Spangled Banner" at ballgames or other occasions, we only sing the first verse. But the song actually has four verses.

In his inaugural address this week, St. Paul Mayor Melvin Carter suggested that one of the unfamiliar verses reveals that our national anthem is racist. He quoted these words from the third verse:

"No refuge could save the hireling and slave,

From the terror of flight, or the gloom of the grave."

Francis Scott Key was inspired to write those words during the battle for Baltimore in the War of 1812. Some historians believe he was talking about the slaves who were fighting with the British in hopes they would be freed. Others say "hireling and slave" refers generically to the type of mercenaries that the British typically hired to fight in their armies.