Most presidents get a boost from overseas trips. President George W. Bush, though, may return from Asia wondering why he left US 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 today 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:

[bul] The Senate signalled 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."

[bul] 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.

[bul] The top House Democrat on military spending, Congressman John Murtha, 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 Republican 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 pre-war 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 authorise 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 Republicans.

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

When the Senate passed a $50 billion tax bill early on 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 Republican Sen. John McCain. "We talk a lot about the president's unfavourable 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 specialises in the presidency and Congress.

In Bush's first term, Republican 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 Congressman Tom DeLay as House majority leader after his indictment in Texas; and a federal investigation of Senate Majority Leader Bill Frist's stock transactions.

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. — Associated Press