A cop on Election Day duty at a Greenwich Village polling station nabbed a bank robber this morning after hearing his description over the radio, police said.

The bandit had just held up an HSBC branch on Broadway near West 9th Street around 8:40 a.m. after passing a note, cops said.

The thief fled with an unspecified amount of cash but was nabbed three blocks away by the eagle-eyed officer who saw he matched the broadcast description.

Cops recovered the stolen loot, and charges are pending