WASHINGTON — Hillary Clinton’s strong appeal to working-class voters not only continued Tuesday in West Virginia, it was practically off the charts. This is a key swing group in battleground states and if likely nominee Barack Obama hopes to win a general election against John McCain, who has his own appeal to these workers, he’ll have to find a way to make inroads with blue-collar voters.

They’re arguably the key constitutency, because they’re strong in the states that will likely decide the election, and, unlike other Democratic Party blocs, they might not just not stay home if they’re dissatisfied but could easily vote Republican — as they did for Ronald Reagan.

Former candidate John Edwards’ endorsement of Obama on Wednesday may help somewhat, though for the most part this is something Obama will have to accomplish on his own, by adjusting both his style and his message.

One group working to minimize the impact Edwards will have is — no surprise — the Republican National Committee.

RNC Chairman Mike Duncan said Wednesday, “Barack Obama and John Edwards share an out-of-touch agenda that would raise taxes on families while cutting funding for our troops. The only question is why didn’t Edwards endorse sooner? Edwards’ endorsement of a candidate he previously blasted as inexperienced, hypocritical, and lacking substance will not help Obama with voters looking for real change.”