Mitt Romney is leading President Obama by two points in the latest Gallup poll, as the organization began reporting results among likely voters on Tuesday afternoon.

Traditionally, Republicans have done better in surveys of likely voters than registered voters, because a lot of groups that favor Democrats (such as younger voters) tend to not actually vote.

Today’s Gallup numbers demonstrate how, as the universe of people surveyed contracts, it plays to Romney’s advantage.

Among all adults, Obama currently has a 53 percent approval rating in Gallup’s 3-day tracking poll. Among registered voters, he’s at 49 percent percent to Romney’s 46 percent in Gallup’s seven-day tracking poll. But among likely voters, Obama is at just 47 percent, to Romney’s 49 percent.

The poll showing Romney leading by two points includes two days of polling prior to last Wednesday’s debate, which Romney dominated.