(AP) - In a first-day flurry of activity, PresidentBarack Obama set up shop in the Oval Office, summoned advisers tobegin dealing with war and recession and ordered new ethics rulesfor "a clean break from business as usual."

He also froze salaries for top White House staff members, placedphone calls to Mideast leaders and had aides circulate a draftexecutive order that would close the detention center at GuantanamoBay within a year.

"The way to make government responsible is to hold itaccountable," Obama said as he unveiled ethics rules that heportrayed as the fulfillment of a major campaign promise. He saidthe action was necessary "to help restore faith in governmentwithout which we cannot deliver the changes that we were sent hereto make."

Devoting swift attention to the Mideast turmoil, Obama preparedto give George Mitchell, the former Senate Democratic leader, a topdiplomatic post for the region.

In his phone calls to Israeli, Palestinian, Egyptian andJordanian leaders, Obama emphasized that he would work toconsolidate the cease-fire between Israel and Hamas in Gaza, saidthe new White House press secretary, Robert Gibbs.

Gibbs said Obama expressed "his commitment to active engagementin pursuit of Arab-Israeli peace from the beginning of his term."

The enormity of Obama's challenge on the economy was evident inthe mixed messages coming from Capitol Hill.

Rep. David Obey, chairman of the House Appropriations Committee,expressed doubt that the currently planned $825 billion economicstimulus package would be enough, calling the proposal "no silverbullet." At the same time, House Republicans requested a meetingwith Obama to air their worries that the plan was too big.

A multi-denominational prayer service at Washington NationalCathedral and an open house at the presidential mansion were alsoon the schedule of the 44th president, taking office on a promiseto fix the battered economy and withdraw U.S. troops from theunpopular war in Iraq on a 16-month timetable.

The shift in administrations - former President George W. Bushwas back home in Texas - was underscored in far-off Guantanamo Bay,Cuba, where a judge granted Obama's request to suspend the warcrimes trial of a young Canadian. The judge issued a one-sentenceorder for the 120-day continuance without so much as a hearing,possibly the beginning of the end for the former administration'ssystem of trials for alleged terrorists.

A draft executive order made clear the new president intends togo further. It called for closing the facility within a year,releasing some of the 245 detainees still there and transferringothers to different sites for trial.

Among Obama's executive orders:

-A freeze on salaries for White House staff earning $100,000 ormore - about 100 people in all. -New Freedom of Information Act rules, making it harder to keepthe workings of government secret. -Tighter ethics rules governing when administration officialscan work on issues on which they previously lobbied governmentalagencies, and banning them from lobbying the Obama administrationafter leaving government service.

Obama and first lady Michelle Obama sat in the first row forWednesday's invitation-only prayer service. Vice President JoeBiden and his wife, Jill, joined them, as did former President BillClinton and Sen. Hillary Rodham Clinton, D-N.Y., awaitingconfirmation as secretary of state later in the day.

"Grant to Barack Obama, president of the United States, and toall in authority your grace and good will. Bless them with yourheavenly gifts, give them wisdom and strength to know and to doyour will," prayed the Rev. Andy Stanley, one of numerous clericsfrom several religions to speak.

Obama's first White House meetings as president meshed withquickened efforts in Congress to add top Cabinet officials to theroster of those confirmed on Tuesday and to advance the economicstimulus measure that is a top priority of his administration.

Treasury Secretary-designate Timothy Geithner, appearing beforethe Senate Finance Committee for a confirmation hearing, saidenactment of the new president's economic stimulus was essential.He also said the Senate's decision last week to permit use of thesecond $350 installment of a financial industry bailout "willenable us to take the steps necessary to help get credit flowing."

He said Obama and he "share your belief that this program needsserious reform."

Geithner also apologized for his failure to pay personal taxesearlier in the decade, calling the omission a mistake. The taxeswere repaid in stages, some after an IRS audit and the rest after areview of his returns late last year by Obama's transition team. Obama and his wife arrived at the White House around 1 a.m.after attending 10 official inaugural balls.

Several hours later he walked into the most famous office inAmerica for the first time as president.

The new White House press secretary, Robert Gibbs, said in astatement that Obama spent 10 minutes alone and read a note leftfor him by Bush that was in an envelope marked "To: #44, From:#43."

He was then joined by White House chief of staff Rahm Emanueland, several minutes later, the first lady.

Wednesday's meeting with economic advisers was coming at a timewhen 11 million Americans are out of work and millions more feelthe loss of savings and face the prospect of foreclosures on theirhomes.

Last week, Congress cleared the way for use of a second, $350billion installment of financial-industry bailout money, apre-inaugural victory for Obama.

Democratic leaders hope to have the $825 billion economicstimulus measure to his desk by mid-February.

"Fortunately, we've seen Congress immediately start working onthe economic recovery package, getting that passed and puttingpeople back to work," Obama said in an ABC News interview."That's going to be the thing we'll be most focused on."

The war in Iraq that he has promised to end featured prominentlyin Obama's first day as well.

Defense Secretary Robert Gates and the chairman of the JointChiefs of Staff, Adm. Mike Mullen, were among those called in forthe meeting as the new president assumed the role of commander inchief.

Obama calls for a remaking of America The inauguration of Barack Obama