President Barack Obama scrapped on Friday his administration's plans to tighten smog rules, bowing to the demands of congressional Republicans and some business leaders, AP reported. It was another major backdown by Obama in his continual battle with powerful Republican congressional leaders, who have won a string of head-to-head rounds with the president mainly on financial matters. Obama's latest move overruled the Environmental Protection Agency and countered the unanimous opinion of EPA's independent panel of scientific advisers. He directed EPA administrator Lisa Jackson to withdraw the proposed final regulation to reduce concentrations of ground-level ozone, smog's main ingredient. The decision rests in part on reducing regulatory burdens and uncertainty for businesses at a time of rampant uncertainty about an unsteady economy. Obama had set out initially to correct a weaker standard set by Republican President George W. Bush, his predecessor, which the head of Obama's EPA said as recently as July would not survive a legal challenge, because it did not follow the recommendations of the agency's scientific advisers. That independent panel in March reiterated its position, saying in a letter to Jackson that it was its "unanimous recommendation" to make the smog standard stronger, and the evidence was "sufficiently certain" that a range proposed in January 2010 under Obama would benefit public health. The White House, which has pledged to base decisions on science, said Friday that the science behind its initial decision needed to be updated, and a new standard would be issued in 2013. -- SPA