President Obama’s sharpening his rhetoric about his GOP congressional opponents. In his weekly Saturday Internet and radio address he said that lawmakers could learn something from the average Americans he’s met during his recent three day listening/political tour through the Midwest.

The nation would be better off if its leaders showed the same discipline, integrity, and responsibility that citizens outside Washington “demonstrate in their lives every single day”, said Obama.

If they did so these unnamed DC reprobates could do things right now to help the economy, such as pass a road construction bill, or extend a reduction in the payroll tax that funds Social Security, or approve trade pacts with other countries, said the president. (He was referring there to proposals he’s been pushing for weeks.)

“These are common-sense ideas, ideas that have been supported by both Democrats and Republicans. The one thing holding them back is politics. The only thing preventing us from passing these bills is the refusal by some in Congress to put country ahead of party. That’s the problem we have right now. That’s what’s holding this country back,” said Obama in his weekly address.

The president didn’t say the word “Republican”, but it’s fair to assume he is not talking here about House Minority Leader Nancy Pelosi. So he’s accusing some in the GOP of putting partisan concerns ahead of what’s good for the country.

OK, he didn’t call them “treasonous”, as Texas Governor Rick Perry said of Fed honcho Ben Bernanke, but those are still pretty tough assertions. He all but said the folks in Martha’s Vineyard would treat Speaker John Boehner pretty ugly if he showed up in Chilmark.

In the past, Obama has generally talked about Republicans trying to take the nation back to the failed policies of the past, in a veiled reference to George W. Bush, when talking in a particularly partisan manner. So why is he sharpening his tongue at this moment and impugning the motivation of his foes?

Well, he might really believe it, for one thing. But more to the political point, it’s becoming increasingly clear that the threat of a double-dip recession will infuse the 2012 campaign. Job woes have helped push Obama’s approval rating below 50 percent in most of the battleground states that will determine next year’s election.

Hmm. Is there anybody else around here Obama’s reelection effort can blame, maybe somebody the public approves of even less than the current occupant of the White House?

Bingo! Right now Americans dislike Congress so much that lawmakers can only dream of reaching the approval rating of used car salesmen. According to Gallup, voters’ evaluation of the job Congress is doing is the worst ever measured, tying an all-time low set in December 2010.

And it’s not like Congress is held in high regard in the best of times. To say it has reached an approval nadir is like saying temperatures at the South Pole have plummeted to new lows, or noting that the Chicago Cubs are having an historically bad season.

Only 13 percent of respondents to an August 11-14 Gallup survey gave Congress a thumbs-up. That’s pretty awful.

“If Congress’ ratings do not improve much before the November 2012 elections, its membership could be in line for another shake-up,” writes Gallup analyst Jeffrey Jones.

We bet Obama is trying to help that dynamic gain momentum.