From a Reuters/Zogby poll released today:

WASHINGTON (Reuters) - Democrat Barack Obama's big national lead over Hillary Clinton has all but evaporated in the U.S. presidential race, and both Democrats trail Republican John McCain, according a Reuters/Zogby poll released on Wednesday.

The poll showed Obama had only a statistically insignificant lead of 47 percent to 44 percent over Clinton, down sharply from a 14 point edge he held over her in February when he was riding the tide of 10 straight victories.

Results of three national polls for Clinton v. Obama were released today.

Before getting to the poll results, take a look at this report card from Survey USA of accuracy by the pollsters in this election year.  Notice how Gallup, Rasmussen, and CNN are ranked:  Gallup tied for first, Rasmussen at 22, and CNN near the bottom at 28.

Now for today's poll results.

Gallup tracking has Clinton 47, Obama 45.  This represents a 5-point drop for Obama since last week.  This same poll shows Clinton and McCain tied (46 each), while Obama loses to McCain by 2 (46:44).

Gallup says this:

Obama led Clinton in all Gallup Poll Daily tracking reports from March 9 through March 16, indicating he had a real, albeit slim, advantage in national Democratic preferences over this period. While not statistically significant, Clinton's two percentage point advantage in today's report is a notable shift, particularly in light of the political storm Obama has faced over the past few days concerning controversial political statements made by the former pastor of his Chicago church.

Rasmussen tracking shows a 9-point drop in Obama's favorability rating since Feb. 21.  Against Clinton, Obama has dropped 4 points from last Wednesday (O46:C44).

Rasmussen says this:

Looked at from a slightly longer perspective, Obama's overall favorable ratings peaked at 56% on February 21, shortly after he won the Wisconsin Primary. At that point, Clinton began raising questions about Obama as part of the campaign that ultimately enabled her to win the Texas and Ohio Primaries. Since then, Obama's net favorability ratings have fallen seventeen points (from plus 14 points on February 21 to minus 3 points today).

Rasmussen also surveyed opinions about Rev. Wright and his impact on Obama.  A myDD diary earlier today provided a concise analysis of those findings.

CNN has a new poll out today, with no  predecesor to use as a benchmark, that has O52:C45.  CNN doesn't provide much real analysis or any basis for trends so its disparity with the Gallup and Rasmussen polls is inexplicable. While Obama may be happy about these numbers, he may be unhappy about two other findings, especially in light of the Rev. Wright problem:

More people believe that superdelegates should decide based on their view of who would be the best candidate, rather than who has won more delegates or the popular vote (49:46).

And 63% believe that Florida and Michigan should hold new primaries.  If Obama is seen as blocking re-votes, this could certainly be a problem for him.

In sum, two longstanding national tracking polls are showing downward trends for Obama relative to Clinton, in terms of overall favorability, and against McCain. This is not good news for the Senator in the wake of the Wright videos, which seem to be multiplying by the hour.  We'll see whether Obama's "major speech on race" tomorrow will mitigate the damage or just fan the flames and help keep the story burning.

Final thought: These trends leave no doubt why Obama has launched a major offensive against Hillary Clinton.