Democrats are winning at least one key aspect of the 2012 campaign: voter contact.

Some Republicans are starting to fret a little bit about their ground game and a new Washington Post-ABC News poll shows that fear is at least somewhat justified.

According to the poll, 20 percent of registered voters say they have been contacted by the Obama campaign, compared to 13 percent who say they have been contacted by Mitt Romney’s campaign.

Photo by Alison Noon for  The 12

That’s on-par with the gap at the same point in the 2008 campaign, when 18 percent of likely voters said they had been contacted by the Obama team and 11 percent who said they had been contacted by Sen. John McCain’s (R-Ariz.) campaign.

But it didn’t use to be the case. The Republicans’ voter turnout machine was once vaunted – particularly its 72-hour voter mobilization program.

In fact, in September 2004, slightly more voters said they had been contacted by President Bush’s team (18 percent) than Sen. John Kerry’s (D-Mass.) team (17 percent).

At an event Monday, former Mississippi governor and Republican National Committee chairman Haley Barbour said Republicans need to be concerned about that.

“That's something we need to be very, very, very cognizant of,” Barbour said. “We used to have an advantage on ground game -- get out the vote, 72-hour program, all that. They now have an advantage. We have to do what it takes to overcome the union muscle and money that goes in the streets."

Barbour pointed out that, even as Republicans made big gains in 2010, Democrats won some of the closest races in the country because they were able to kick their voter mobilization efforts into gear when it was clear that the races would be tight.

Barbour said that labor looms as a potentially game-changing force, even after it experienced a setback in the recall of Wisconsin Gov. Scott Walker (R). Labor is a major part of Democrats’ voter mobilization efforts and the Obama campaign has focused heavily on this effort as well.

“They don’t have to be enthusiastic; they pay people to do this,” Barbour said.

Voter contact is one important aspect of a campaign's ground game, but it is not the whole game. What's more, Obama's team has had much more time and money to contact voters nationwide, while Romney's campaign was focused on individual states during the Republican primary campaign.

And Republicans tend to be able to rely more on enthusiasm than Democrats, whose party base contains several key demographic groups that don't always turn out in higher numbers (young people and minority groups being chief among them).

In other words: voter contact is not the be-all-end-all and things can change. But Obama's team has made a concerted effort to define its campaign with grassroots activism, and at least so far, it's reached more people on a person-to-person level.

The poll shows the Obama team has been particularly effective in contacting demographics that are important to its turnout efforts, including liberal Democrats (42 percent say they have been contacted), non-whites (24 percent) and people who voted for Obama last time (31 percent).

Romney, meanwhile, has focused on conservative Republicans (25 percent), seniors (21 percent), white evangelicals (18 percent) and 2008 McCain voters (19 percent).