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President Bush said Saturday that pulling out of Iraq now is not an option, rejecting calls by some lawmakers and many people asked in polls to start bringing U.S. troops (search) home.

"The terrorists and insurgents are trying to get us to retreat. Their goal is to get us to leave before Iraqis have had a chance to show the region what a government that is elected and truly accountable to its citizens can do for its people," Bush said in his weekly radio address.

"We will settle for nothing less than victory" over terrorists there, he said later.

Bush's radio address is part of a series of appearances and speeches in the coming weeks aimed at countering poll ratings that are near their lowest levels on both the Iraq war and the economy. Bush said his administration is committed to success in both areas of concern for Americans.

About six in 10 in a Gallup poll (search) taken in early June said the United States should withdraw some or all of its troops — the highest level of support for withdrawing U.S. troops since the war began.

On the economy, the president said he needs help from Congress to keep the nation on the right track. With some of his signature domestic priorities experiencing difficulties on Capitol Hill (search), he urged support for his request for a free-trade agreement with Central American and Caribbean nations, an overhaul of Social Security and wide-ranging energy legislation.

And even as Bush just this week delayed another domestic priority — a massive rewriting of the tax code to simplify it — by two months, he said it must be done.

"We need to work together to ensure that opportunity reaches every corner of our great country," Bush said.

But it is the president's Iraq policy that has taken the biggest slide in the polls. Once a mainstay of his public support, his handling of the Iraq war was backed by only 41 percent in an Associated Press-Ipsos poll this month — his lowest level of support yet on Iraq.

Bush acknowledged discontent over his decisions but signaled no shift in policy or timing for the American presence in Iraq.

"Some may disagree with my decision to remove Saddam Hussein from power, but all of us can agree that the world's terrorists have now made Iraq a central front in the war on terror," he said. "This mission isn't easy, and it will not be accomplished overnight."

Amid continuing attacks and suicide bombings in Iraq, a few Republicans and Democrats — including one GOP (search) lawmaker who voted for war in Iraq — introduced a resolution this week calling for Bush to begin withdrawing U.S. troops from Iraq by Oct. 1, 2006. There have been nearly 1,100 violent deaths in Iraq linked to the insurgency since a transitional government took office seven weeks ago.

The administration insists no timetable can be set for bringing U.S. forces home from Iraq until enough Iraqi forces have been sufficiently trained to take over the fight against the insurgency. Anything else, the administration argues, would only embolden the insurgency.

Bush also paid tribute to progress seen in Iraq this week. Iraq's Shiite-led parliament and leaders of the disaffected Sunni Arab minority (search), which is believed to be the backbone of the insurgency, agreed on a process for drafting Iraq's constitution.

"Time and again, the Iraqi people have defied the skeptics who claim they are not up to the job of building a free society," he said. "I am confident that Iraqis will continue to defy the skeptics as they build a new Iraq that represents the diversity of their nation and assumes greater responsibility for their own security. And when they do, our troops can come home with the honor they have earned."

After elections in January, writing a constitution is Iraq's next milestone in its fits-and-starts transition to democracy. Later this year, the document is to put up for a vote in a public referendum and then a new government is to be elected.