WASHINGTON - Most presidents get a boost from overseas trips. President Bush, though, may return from Asia wondering why he left U.S. soil in the first place.

Caught off guard when South Korea announced plans to pull one-third of its troops from Iraq, the president also could look back on the home front and find things have not exactly been quiet.

Bush returns late Monday to even more political acrimony than when he left eight days ago. The corrosive debate over Iraq is eroding his second term-agenda and challenging the ability of Republican leaders in Congress to maintain discipline.

While Bush was away:

_The Senate signaled impatience with the war's direction by voting 79-19 to require regular reports on progress in Iraq and urging that 2006 be "a period of significant transition to full Iraqi sovereignty."

_Increasingly rebellious Republicans defied their leaders on domestic spending cuts. House leaders narrowly won approval of a five-year budget cut plan in the wee hours of Friday on a 217-215 vote.

_The top House Democrat on military spending, Rep. John Murtha (news, bio, voting record) of Pennsylvania, withdrew his support for the war and advocated a pullout over six months. That brought sharp criticism from the White House and led to tumultuous late-night battle when the GOP leaders forced a vote on an immediate pullout measure in hopes of trapping Democrats. It was rejected 403-3.

In a rare across-the-world exchange of invective, the White House traded daily barbs with its Democratic critics. They accused Bush of manipulating prewar intelligence and deceiving the nation in starting a war he is unable to end.

Bush and his aides said Democrats were irresponsible and hypocritical, particularly those who voted in 2002 to authorize the war and now oppose it.

So much for the old maxim that "politics stops at the water's edge." In deference to a president's conduct of foreign policy, even lawmakers opposed to his approach traditionally held their fire while the chief executive was overseas, especially during wartime.

Bush's slumping approval rating — 37 percent in an AP-Ipsos poll, the lowest of his presidency — and eroding public support for the Iraq war are taking a toll on the GOP.

Republicans fear losing their majorities in next year's congressional elections. That is spilling over and causing problems in other areas, from reauthorizing the Patriot Act to trimming programs for education, health and the poor.

When the Senate passed a $50 billion tax bill early Friday, it left out one of Bush's second-term priorities: an extension of tax cuts on dividends and capital gains that are now set to expire after 2008.

"My colleagues are getting nervous," said Sen. John McCain (news, bio, voting record), R-Ariz. "We talk a lot about the president's unfavorable ratings. Have you noticed the ratings of Congress lately?"

The AP-Ipsos poll showed that only 32 percent of those surveyed said they approved of the job Congress was doing.

Discontent is growing among Republicans, moderates and conservatives, said Norman Ornstein, an analyst at the American Enterprise Institute who specializes in the presidency and Congress.

"They probably wouldn't be angry if Bush were at 55 percent, or 65 percent, or even 45 percent," he said.

"But put him down where he is, with the growing public unhappiness with them and their nervousness over the elections ahead, and it is a bad combination," Ornstein said.

In Bush's first term, GOP leaders prided themselves on their unity and discipline. They are hampered now, for a variety of reasons: Bush's plunge in the polls; an unpopular war; the stepping aside of Rep. Tom DeLay as House majority leader after his indictment in Texas; and a federal investigation of Senate Majority Leader Bill Frist's stock transactions.

Further contributing to that anxiety are concerns that older people — who make up an active voting bloc — will be frustrated by the level of benefits under the new Medicare prescription drug plan that takes effect early in 2006.

The growing GOP restiveness is making it harder for Bush to have his way.

"The congressional Republicans have put the president in an awkward spot because they seem to be changing their minds on Iraq," said Wayne Fields, director of American culture studies at Washington University in St. Louis and a specialist on presidential rhetoric.

While Bush takes strong positions, he is not well equipped to make persuasive arguments with the public or Congress or good at give-and-take, Fields said.

"He's always shielded from elements in society which are critical. He addresses hand-picked audiences where people don't heckle him. There's a protective screen around him. And I think people are starting to react to that," Fields said.

EDITOR'S NOTE — Tom Raum has covered Washington for The Associated Press since 1973, including five presidencies.

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