Did the Obama attack ads have an impact on the race?

In a word, yes.  Then again, one word is often too simple to explain what is going on.  You can clearly see a distinct change in the RealClearPolitics polling trending directions.

After trending slowly closer over the last 6 months, Romney and Obama have started moving in clearly opposite directions over the last little while. The Bain attack ads and the Romney taxes attacks are making a difference. BUT...

If you look at most of the polls they are focused on registered voters and not likely voters. Likely voter numbers have the contenders much closer together than the registered voter polls. Likely voter models are typically a much better indicator of the likely outcome. The problem is, very few polls are currently using likely voter models as for most pollsters, it is too early in the campaign for them to consider doing it. Thus tracking likely voter polls offers too infrequent snapshots for tracking purposes.

The second challenge with looking at the polls at face value is the partisan weighting used for polls. Every poll is conducted weighting the number of responders between Republican, Democrat and Independent voters. If one poll sets the ratio as D/R/I 37/25/28 for example while another weights it with a D/R/I of 33/29/27 the two polls will undoubtedly show different results. This is a critical factor in the outcome of the poll and often pollsters will not publish their voter index with their poll results. Those who do publish have often used the voter index splits from 2008 (very heavily Obama-indexed) instead of more recent splits. The 2010 midterm election results were not so Democrat heavy and that index may be closer to the right split. Using 2010 though may overly favor Republicans. Suddenly the science of polling seems a little more pseudo-science, doesn't it.

And all that is without going into the scientific parts around confidence level and margin of error.

The fact of the matter is despite all of those caveats, the directional indicator is that those attack ads are indeed having an impact. But if the trend is halted, really the gap has moved in favor of Obama by about 4%.  With Romney soon being allowed to unleash a flood of money into the campaign, his ad spending may be able to swamp the president and reverse that trend altogether.  For Republicans, the overall poll direction should be worrisome but not invoke a state of panic at this point.  What should invoke a state of panic?  If Romney fails to respond to it.