Maybe this will stop the silly post-convention panic among Republicans.  When the Washington Post/ABC poll tells you there’s been no convention bump for Barack Obama, you can pretty much take that to the bank.  Their latest survey shows the likely-voter split in the presidential race right where we found it a fortnight ago, with Obama up one single point over Mitt Romney — in a sample that favors the Democrats:

Last week’s Democratic National Convention helped President Obama improve his standing against Republican Mitt Romney, according to a new Washington Post-ABC News poll, but did little to reduce voter concern about his handling of the economy.

The survey shows that the race remains close among likely voters, with Obama at 49 percent and Romney at 48 percent, virtually unchanged from a poll taken just before the conventions.

So, the second paragraph actually disproves the first.  But the Post tries hard to pretend that no movement among likely voters means improvement for Obama:

But among a wider sample of all registered voters, Obama holds an apparent edge, topping Romney at 50 percent to 44 percent, and has clear advantages on important issues in the campaign when compared with his rival.

We’re less than 60 days out.  Registered-voter samples don’t mean much at this stage of the election; it’s likely voters that provide predictive data from surveys.  They mean even less when only 26% in the sample are Republicans.  The likely voter sample improves that by a point to 27%, but still has a D+6 D/R/I at 33/27/36.  The 2010 midterms had a national turnout D/R/I of 35/35/30; the 2008 election was D+7 at 39/32/29.  A GOP turnout of 27% would be among the worst ever in a presidential race, if not a record.  Since enthusiasm measures in other surveys, notably Gallup’s, show an enthusiasm gap favoring Republicans, I’m not inclined to buy this poll’s likely-voter split as a model for this election.

Also, the internals for Obama even among RVs are hardly cheery.  His job approval hasn’t budged since before the conventions.  Three weeks ago, it was 47/50, and now it’s 48/50.  On the economy, he went from 43/56 to 45/53.  Among independents, Obama’s job approval is 45/50 with 37% strongly disapproving.  That’s probably why Romney’s beating Obama among likely independent voters by eleven points, 54/43.  Obama won independents by eight in 2008 on his way to a seven point victory overall.  That’s a 19-point swing among independents.

In other words, the convention had no real impact at all on the race.  That’s why I say “I told you so” in my column for The Week:

Gallup conducted a survey of more than 1,000 adults over the two days following the end of the Democratic National Convention to determine which convention had the most impact. In practically every measure, the conventions produced no net change in anticipated voter behavior. After the Republican convention, 40 percent said they’d be more likely to vote for Mitt Romney, while 38 percent said less likely, with 21 percent saying the convention had no real impact at all. For Democrats, the numbers are 43/38/20, respectively. Both sets of numbers are within the 4 percent margin of error, producing a complete wash.

Conventions used to serve the purpose of cutting through the media filters so that undecided voters could see candidates for themselves and decide on their vote. But Gallup’s data on independents shows that such voters were largely unswayed by the conventions. The Democratic convention produced a 39/39 split among unaffiliated voters (half said they were more likely to vote for Obama, and half said less), while the GOP convention had a three-point positive edge, 36/33 — still well within the margin of error. Furthermore, fewer people watched the conventions at length this year, with only 55 percent of Gallup’s respondents saying they’d watched “a great deal” or “some” of the Democratic convention, and 51 percent for the GOP convention. Those are the lowest ratings from Gallup for nominating conventions in 12 years.

The speeches didn’t exactly move the needle, either — at least not those by the nominees. Only 43 percent rated Barack Obama’s speech “excellent” or “good,” just 5 points higher than Mitt Romney’s 38 percent. Both candidates scored a 16 percent combined “poor” or “terrible” rating, while roughly a quarter of respondents didn’t see either speech.

So why bother spending tens of millions of dollars — including taxpayer money — to stage them?

Update: The poll also asks the “better off” question, among RVs only, and only 20% think they’re better off from 4 years ago, while 32% believe they’re worse off, and 47% say no change.  Among independents, that’s 19/38/43, perhaps one reason why Romney’s up eleven among independents.

Update II: Since I usually heap scorn on the WaPo/ABC series’ samples, I really should note that the Post has done a terrific job in providing easy access to the raw data breakdowns.  They have each question charted, with the cross-tab info easily accessible on each via drop-down boxes.  Well done.