Romney "playing defense" with own voting group

Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks during a campaign rally on Wednesday, Sept. 26, 2012 in Toledo, Ohio.
AP Photo/ Evan Vucci

(CBS News) In the key election swing state of Florida, nearly one out of three voters is over 65.

A poll out Wednesday shows a big shift in that group toward the president. A month ago, President Obama trailed GOP challenger Mitt Romney among seniors by 13 points. In a new poll, Mr. Obama is ahead by four percentage points, leading 51 percent to 47 percent. That is a swing of 17 points in one month.

The statisticians will remind us polls are just a snapshot and not predictive of what will happen, but it does give us an indication of the underlying currents in the race.

Barack Obama lost the senior vote to John McCain in Florida by eight points in 2008. So for the president to be doing well in the traditional Republican voting block is a danger sign for Romney.

Strategists for both parties in Florida agree Mr. Obama is ahead in the state and the battle over Medicare is helping make inroads with seniors.

The president is also doing better with blue collar white voters in Ohio and is doing better on the economy.

It's why Mitt Romney is having to play defense with his own voting group. The time he has to spend time shoring them up is time he's not spending getting swing voters.

Polls that are taken about this point in September sometimes predict the winner and sometimes they don't.

In 2008, polls had Obama over McCain at about this point, but in the year 2000, we had Gore over Bush about this point.

If we go all the way back to 1952, Eisenhower's first election, the vast majority of the time the candidate who was ahead in the polls six weeks out ended up winning in the end.

However, Presidents John Kennedy, Ronald Reagan and George W. Bush were all tied or behind at this point, and they pulled it out in the end.