Hillary Rodham Clinton has closed the gap – a bit – with Barack Obama. Gallup’s daily tracking poll today shows that Obama leads Clinton 48 to 44 percent among Democratic and Democrat-leaning voters.

Since the margin of error for the poll is +/- 3 percent, that puts the candidates in a statistical dead heat. Yesterday’s daily tracking poll had at Obama at 50 percent and Clinton at 44.

The survey was conducted May 13-15. During that time, Clinton won the West Virginia primary and John Edwards endorsed Barack Obama.

Gallup notes that the “slight narrowing of the race … is typical of the way the contest has gone over the past several months, with neither candidate able to maintain a significant lead among national Democratic voters for very long.”

There has been a small change in hypothetical match-ups with Republican John McCain. McCain is ahead of Obama, 47-45 percent among registered voters (the two were tied at 45 yesterday). With the margin of error at +/- 2 percent, that also puts them in a statistical tie. But against Clinton, McCain fares signficantly worse: Clinton has a 3 point lead 48 – 45 percent.