After a rough and busy week, President Barack Obama wined and dined First Lady Michelle to mark their belated 20th wedding anniversary.

The Obamas, whose two-decade milestone fell on the same day as Wednesday's first presidential debate held in Denver, Colorado, set out on a crisp evening by motorcade to Bourbon Steak restaurant in Washington's Georgetown neighborhood.

An energized Romney delivered a surprisingly strong performance in the first of three televised confrontations opposite a lethargic Obama, injecting new momentum into his campaign ahead of the tight November 6 election.

On stage, Romney joked: "I'm sure this was the most romantic place you could imagine, here -- here with me ..."

Obama, who wished his wife a happy anniversary at the start of his debate remarks, is out to prove him wrong.