by Jitendra Joshi Sun Mar 16, 5:10 PM ET

WASHINGTON (AFP) - Hillary Clinton's White House campaign lashed out Sunday after a report said rival Barack Obama was preparing a "full assault" on her after unloading some embarrassments to his own campaign.

The feuding over the report in the Democrat's hometown newspaper, the Chicago Tribune, came as Republican nominee-elect John McCain polished his national security credentials on a surprise trip to Iraq.

"It is disappointing that a campaign that began by promising a politics of hope has come to this, that it is signalling and revelling in attacks on Senator Clinton's character," her communications director Howard Wolfson said.

"This is not the campaign they promised us," he said on a conference call.

The Tribune noted that Obama was now distancing himself from his fiery Chicago pastor, who argues in a newly unearthed video that the September 11 attacks of 2001 showed that "America's chickens are coming home to roost."

The Illinois senator had also sat down Friday for a grilling from Chicago reporters about his past ties to a city property developer, Antoin "Tony" Rezko, who is on trial for corruption in public contracts.

The Tribune report said Obama was "trying to air his dirty laundry ... as he prepares a full assault on Senator Hillary Clinton over ethics and transparency." It did not spell out what form that assault might take.

But earlier Sunday, Obama aides kept up a barrage of questioning over Clinton's tax returns, her records from her White House days, and possible ties to donors who gave generously to her husband Bill's presidential library.

"The Clinton campaign says she has been fully vetted but the truth is she is a veteran of non-disclosure," Obama chief strategist David Axelrod said.

"All of this has created a sense that there are things she wants the public not to know," he said.

And addressing the Clinton camp's battle to seat delegates from the pariah states of Florida and Michigan, Axelrod said: "You get the feeling they are literally trying to do anything to win this nomination."

The feistier tone between the campaigns belied a truce over Obama's pastor with Clinton supporters passing up repeating opportunities to decry the inflammatory language of Reverend Jeremiah Wright, who said in the newly disclosed video that the 9/11 attacks were brought on by US "terrorism."

House of Representatives Speaker Nancy Pelosi, the country's highest ranking elected Democrat, ruled out a "dream ticket" combining Obama and Clinton and said the party's nominee should be whoever leads in the final delegate count.

That would appear to favor Obama, while The New York Times reported that many Democratic "superdelegates" are loath for party grandees to overturn the will of the majority of voters at the August convention in Denver.

In the race for pledged delegates, Obama enjoys a lead of about 170 over Clinton. He has won double the number of states and is ahead in the national popular vote.

Speaking on ABC News, Pelosi said "if the votes of the superdelegates overturn what happened in the elections, it would be harmful to the Democratic Party."

"This is going to be over before we go to the convention... pretty soon, somebody will be far enough in front that this will come to an end," she said.

The next battle in the Democrats' nominating epic is Pennsylvania on April 22. But Obama is already campaigning in Indiana, which votes on May 6 along with North Carolina, in a sign that the race has weeks to go yet.

Clinton, dogged by her 2002 vote authorizing military force in Iraq, was due to give what her campaign called a "major policy address" on the war on Monday in Washington. The US-led invasion's fifth anniversary looms Thursday.

While the Democrats are sparring furiously over who would be the better commander-in-chief, McCain and two other pro-war senators arrived in Iraq on the first leg of a tour also taking him to the Middle East and Europe.

On CNN, Democratic Senator Patrick Leahy accused McCain of heading over for a taxpayer-funded "photo op" instead of asking "hard questions" of the Iraqi government.