Former President Barack Obama on Thursday night complained that Democratic voters often fail to show up to help their candidates during off-year elections, at a rally for Democrat Ralph Northam, who is running for Virginia governor.

"Democrats sometimes ... y'all get a little sleepy. You get a little complacent," he said at the rally in Richmond, Va.

"This is not my opinion, this is the data," Obama said.

He said Democrats often show up in great numbers during presidential elections, but then fail to show up in the off years.

"And so, as a consequence, folks wake up and they're surprised, how come we can't get things through Congress. How come we can't get things through the statehouse?" he asked.

"Because you slept through the election," he said. "But the stakes now don't allow you to sleep."

Obama specifically cited younger voters, and encouraged them to vote.

"I think it's great that you hashtag and meme, but I need you to vote," he said.

Obama also revived his "don't boo, vote" slogan that he used during the 2016 campaign for Hillary Clinton, who lost to Donald Trump last year.