Congress' already-dismal approval rating sank again this month, tying its all time low of 10 percent, according to a Gallup poll released Tuesday.

"Americans' views of Congress are so bad that it has now been more than a year since Gallup's monthly assessment was as high as 20 percent," a Gallup analysis said.

Gallup said it was difficult to pinpoint exactly why the rating had tied its low mark, recorded in February. The pollster has been asking about Congress for 38 years.

The economy, it said, is a major reason for the low marks, and "the fact that control of Congress is now divided, with a Republican majority in the House and a Democratic majority in the Senate, may provide an opportunity for Americans of all political persuasions to dislike some aspect of Congress."

Congress left last week for an extended summer recess, and plans to be back in mid-September. Lawmakers are not expected to approve a formal budget for the 2013 fiscal year, which begins Oct. 1, and are not seen as taking action on a number of major fiscal issues, such as extending the expiring Bush era tax cuts, until after the November election.

It's hard to say what effect the low rating will have on this fall's congressional elections, Gallup said. Independent analysts do not expect much of a shakeup, since each party's loyalists tend to blame the other side for the inertia.

Gallup surveyed 1,102 adults from August 9 to 12. Margin of error is plus or minus 4 percentage points.