With more than a week of post-convention polling in the books, there is a consistent and significant swing towards Hillary Clinton. In just one month, Donald Trump went from being tied or even slightly ahead in national polls to being down anywhere from 4 to 15 points. But, these high level numbers don't tell the whole story; hidden in the polls is the breakdown of exactly where Trump's support appears to be softening, and the larger question--where exactly are these voters going?

To answer this question, I used the McClatchy-Marist poll showing Clinton leading Trump by 15 points. I focused on this poll for two reasons: first of all, they conducted polling before and after the conventions. And secondly, they provide the measure of support for each candidate broken down by detailed sub-groups (cross-tabulations, for stat geeks). Here's what I found:

Trump's largest declines in support are from millennials (down 14%), "soft" Republicans (down 13%), and non-college educated (down 10%). But, Trump's losses are not generally translating to Clinton gains--amongst these groups, there is a larger increase in the "neither" or "undecided" category amongst all three groups. When Gary Johnson is included as an option, millennials and non-college educated are moving towards him

Clinton gains are coming in traditional Democratic base demographics. When one looks at the Clinton numbers, the largest swings in her support are actually coming from traditional Democratic constituencies--self-identified soft Democrats and African Americans (both increasing by about 12%).

Men are the important and noticeable exception. One key demographic where Trump losses appear to be moving to Clinton's gains are amongst male voters. Between the July and August polls, Trump's support amongst men declined by 10% while Clinton's support increased by 12%. This pattern is the same whether Gary Johnson is included or not.

Given these patterns in the polling, pay attention to not just the aggregate poll numbers, but the shifts that could be occurring amongst key voting blocks. As the national numbers move, ask which demographic groups are potentially driving any changes. Given the large movement towards undecided or neither, a close look at polling involving independent candidates could become important.