First lady Michelle Obama urged cheering supporters in Richmond on Thursday to make an all-out effort to register voters and get them to the polls in the crucial swing state.

First lady Michelle Obama speaks during the Democratic National Convention on Sept. 5 in Charlotte, N.C. (Charlie Neibergall/AP)

Four years ago, Obama said, “we won [Virginia] by 235,000 votes. While that might sound like a lot, think about this: When you break that number down, that’s just 100 votes per precinct. ... I want you to think about, with just a few evenings on a phone bank, just a few evenings knocking on doors ... you could swing an entire precinct for Barack Obama. If we win enough precincts, we will win this state. And if we win Virginia, we will be on our way to putting Barack Obama back in the White House.”

Obama gave the audience “marching orders:We need every single one of you to work like you’ve never worked before.We need you talk to everyone you know. Your neighbors. That nephew you haven’t seen for a while. That high school classmate you don’t talk to — in years. Find ’em. Bring them to events like this. More importantly, make sure they’re registered.”

Obama said the race will come down to which team makes the bigger push in the final weeks of the campaign.

“So when you start to get tired, and you will; when you start to think about taking a day off, and you will; I just want you to remember that what we do for the next 54 days will absolutely make a difference between waking up on November 7th and wondering whether I could have done more, or feeling the promise of four more years.”

The first lady spoke for 40 minutes to a crowd that interrupted her with applause and chants of “Four mor years!” Afterward, she waded into the audience to shake hands and hug supporters for another 10 minutes.

After her appearance in Richmond, Obama headed for another rally in Fredericksburg. Her visit came on the same day that her husband’s challenger, Republican Mitt Romney, held a rally in a Fairfax park.

Romney’s running mate, Rep. Paul Ryan of Wisconsin, is scheduled to campaign in Roanoke on Friday. Also Friday, one of Romney’s sons will campaign in the state. Craig Romney is scheduled to hold a “meet and greet” at Romney campaign offices in Prince William County and Arlington.