For quite a while, there were certain trends that political observers were simply supposed to accept as fact: Barack Obama would struggle to win support from Latino voters. And Jewish voters. And working-class, low-income voters. These were obvious “truths” that “everyone” knew.

Except none of these observations are holding up well. Obama is doing very well with Latino voters, Jewish voters, and according to a new Washington Post report, working-class, low-income voters.

Democratic Sen. Barack Obama holds a 2 to 1 edge over Republican Sen. John McCain among the nation’s low-wage workers, but many are unconvinced that either presidential candidate would be better than the other at fixing the ailing economy or improving the health-care system, according to a new national poll.

Obama’s advantage is attributable largely to overwhelming support from two traditional Democratic constituencies: African Americans and Hispanics. But even among white workers — a group of voters that has been targeted by both parties as a key to victory in November — Obama leads McCain by 10 percentage points, 47 percent to 37 percent, and has the advantage as the more empathetic candidate.

Let’s not brush past this point too quickly — among low-income whites, Obama leads McCain by 10. To be sure, about one in six of the white workers remains uncommitted, but at least for now, Obama seems to have a sizable lead with a constituency that was rumored to be a lost cause up until fairly recently.

Greg Sargent concluded, “If this poll is accurate, McCain is dramatically under-performing among these voters. Will we be hearing a ‘McCain’s working class whites problem’ meme anytime soon?”

Given the data, it’s hardly an unreasonable argument to make.