Forget post-convention bounces - the numbers that really matter are in the battleground states, where President Obama's polling advantage is more concerning to Mitt Romney's team than any national numbers.

No Republican has ever won the presidency without winning Ohio, and Romney isn't in a strong position to become the first.

According to ABC News' latest race ratings, President Obama is in strong position for 237 electoral votes, when leaning and solid Democratic states and combined. Mitt Romney has only 206 votes he can expect in his column, as of now.

Add in Ohio's 18 electoral votes, though, and Obama stands at 255 - within striking distance of the magic number of 270. Romney would need to win nearly every other battleground state - a list that includes Paul Ryan's Wisconsin, once thought to be safely Democratic - to pull out the presidency without Ohio.

Check out my conversation with ABC's David Muir from Sunday "World News" - including the literal lift in Florida that the president received the weekend after his convention. It appears below after David Kerley's report on how Mitt Romney has softened his position on repealing the president's health reform law: