A week after vice-presidential aide Lewis Libby resigned and was indicted on charges related to the leaking of a CIA operative's identity, an ABC News/Washington Post poll showed that fewer than half of Americans viewed Bush as trustworthy and honest.
The president's overall approval rating dropped to a new low of 39%.
"That's a very ominous sign for Bush," Ross Baker, professor of political science at Rutgers University, said of the integrity rating. Bush ran for office in 2000 with a pledge to uphold "honour and dignity" in the presidency after former president Bill Clinton's impeachment scandal.
A CBS poll on Wednesday put Bush's job approval rating at 35%, his lowest since taking office in 2001.
Baker said such numbers could portend difficulties for Republican congressional candidates in the 2006 mid-term elections as well as for Bush's effectiveness in pushing his second-term agenda.
The ingredients to what some White House allies view as a "perfect storm" for Bush include the CIA-leak investigation, a bungled government response to Hurricane Katrina, US military deaths in Iraq, high gasoline prices and conservative anger over the Harriet Miers Supreme Court nomination.
Bush has been criticised for the
bungled Hurricane Katrina response
Some Republicans believe that the widely praised nomination of Ben Bernanke to the Federal Reserve and the replacement of Miers - who withdrew her nomination last week - with appeals court Judge Samuel Alito as the nominee to the Supreme Court were a sign Bush is starting to regain his footing.
Bush's choice of Alito has been unifying for Bush's conservative base.
Bush has moved to mend fences with conservatives upset over a big rise in spending on his watch.
He has begun to emphasise spending restraint in his speeches and last week rolled out plan to block spending on a list of items for which money had been allocated but not yet spent.
But Bush, on a five-day trip to Latin America, was dogged by questions about the leak investigation.
Bush would not say whether Karl
Rove would keep his job
He declined to say on Friday whether longtime aide Karl Rove - who remains under investigation - would keep his job.
Two Republicans with close ties to the White House said morale among the White House staff has plummeted and many aides were feeling the strain of years of long hours and stress.
"They're burned out," said one Republican, who spoke on condition of anonymity.
Another Republican said, "I do think there need to be some staff changes. People have been working at a torrid pace. It's difficult not to get burned out."
Republican National Committee Chairman Ken Mehlman and Ed Gillespie, a former RNC chairman, are among those frequently mentioned as possible new additions to the White House team.
One of the Republican sources said Treasury Secretary John Snow might leave in January or February, and former Bush economic adviser Glenn Hubbard may be a replacement.
Rumours have circulated that White House Chief of Staff Andrew Card might seek the Treasury job or leave the administration.
Republican political strategist Charles Black dismissed the prospect of a big White House shake-up. "I don't believe it's going to happen. They've got a very successful team there. It's well suited to this president," he said.