In battle for blue-collar vote, guns emerge as hot issue

The two Democratic candidates are trading harsh attacks on the issue of guns -- a topic that has been escalating in this campaign ever since the coverage of Obama's "bitter" comments started. But, somewhat paradoxically since this is a Democratic primary, they are both trying to display their anti-gun control credentials.

The Obama campaign has been contacting Pennsylvania voters with robocalls blaming Clinton for her anti-gun record, in particular her vote "banning the confiscation of weapons in emergencies." As the ad claims, "Barack Obama respects our traditions. Senator Clinton voted to allow guns to be confiscated, and this raises real doubts."

Clinton's response is as brutal, as she launched her own robocalls charges Obama with "not telling the truth about his past position on the Second Amendment:"

As an Illinois state Senator, he supported a ban on all handguns, and he even personally filled out a questionnaire saying he supported the ban... And Obama voted to give millions of dollars to anti-gun organizations that are trying to take away our gun rights.

This is just another example of Barack Obama saying one thing, and doing another -- and yet another issue John McCain will use against Obama to win in November.

The vigor of this gun exchange and both candidates' concern with proving their pro-gun credentials shows how essential the blue collar vote has become in tomorrow's vote. This wasn't necessarily the case in all the previous primaries; in many contests, Obama was targeting other groups that were close to Clinton. For a long time, Obama targeted African-Americans, a group he successfully rallied to his side at the beginning of 2008; subsequently, he focused on the female and Hispanic votes which he failed to significantly move in many high-profile contests.

Yet, it is Clinton's strength among blue-collar voters that has emerged as the most significant danger to Obama's nomination as this is Clinton's main argument for why Obama is unelectable (or less electable) in November. And the controversy over Obama's bitter remarks were seized by the Clinton campaign precisely to drive Obama's numbers down among this group of Pennsylvania voters; Clinton is hoping that, after tomorrow's vote, she will have more evidence that Obama has a potentially fatal weakness.

Obama knows he does not necessarily need to win Pennsylvania, nor does he need to prevail among downscale voters; but he does want to cut Clinton's margins to undermine her electability argument and the gun argument is one tactic his campaign has found to attract some blue-collar votes, or at least to drive down their enthusiasm for Clinton and get them to stay at home. Remember, this is the group whose turnout will likely determine tomorrow's result.

In brief, we will parse through exit polls as soon as they are available tomorrow for any evidence of the breakdown among lower-middle class voters, union households, etc. More than the actual results, these are the numbers that could drive the conversation in the days (and weeks?) ahead.