Daily Kos Elections Polling Wrap: An annual mini-diatribe about the concept of 'likely voters'

If it weren't for that critical component of modern political public opinion polling known as the "likely voter" screen, the banner polling headline today would be that, despite the Paul Ryan "bump" and a mammoth spending advantage, Mitt Romney still trailed Barack Obama in the latest CNN/Opinion Research poll of the presidential race by a gaudy 52-43 margin.

Alas, said "likely voter" screen does exist, so instead, the headlines (as they have been for most of this cycle) will warn of a coin flip race, with the president staked to a mere 49-47 lead over the Republican challenger. Even worse, it is inevitable that some in the chattering classes will talk of a "bounce" for Romney since the last poll, which showed Obama up 52-45.

Such talk of movement in Mitt's direction is analytical malpractice, of course, because the previous CNN/OR poll did not have said likely voter screen. In the only apples-to-apples comparison we have here (RV to RV), it is the president whose standing has incrementally improved.

With all this in mind, I close this week of the Wrap (after the fold, of course), with what will be a rerun for long-time readers: a mini-rant about how I am perhaps the only person in the polling analysis game who feels that likely voter screens tend to suck.

But, first, on to the numbers:

PRESIDENTIAL GENERAL ELECTION TRIAL HEATS:

NATIONAL (CNN/Opinion Research): Obama d. Romney (52-43 among RV; 49-47 among LV)

NATIONAL (Gallup Tracking): Obama tied with Romney (46-46)

NATIONAL (Rasmussen Tracking): Romney d. Obama (46-45)

CALIFORNIA (Tulchin Research and M4 Strategies for USC School of Education): Obama d. Romney (56-33)

COLORADO (Keating/OnSight--D): Obama d. Romney (48-44)

MISSOURI (Rasmussen): Obama d. Romney (47-46)

VIRGINIA (Rasmussen): Obama tied with Romney (47-47)

DOWNBALLOT POLLING:

CA-PROP 30 (Tulchin Research and M4 Strategies for USC School of Education): Yes 55, No 36

CA-PROP 38 (Tulchin Research and M4 Strategies for USC School of Education): Yes 40, No 48

NM-SEN (GBA Strategies for the Heinrich Campaign): Martin Heinrich (D) 51, Heather Wilson (R) 44

PA-SEN (Muhlenberg College/Morning Call): Sen. Bob Casey (D) 49, Tom Smith (R) 30

VA-SEN (Rasmussen): Tim Kaine (D) 45, George Allen (R) 45

A few thoughts, as always, await you just past the jump ...