Former President Bill Clinton says he is ready to campaign for Barack Obama whenever the Democrat needs him.

Relations between Clinton and Obama have only just began to thaw since Obama defeated the former president's wife in the bruising Democratic primary. Throughout the race, the former president portrayed Obama as too inexperienced.

Since Obama clinched the nomination, it's been an open question as to what role Clinton would play in the campaign.

Just weeks ago, Obama called the former president to ask for his help.

Clinton says the timetable is up to Obama.

The former president spoke at a news conference in New York on Thursday about work his foundation is doing.

Meanwhile, John McCain's campaign has lashed Barack Obama's planned foreign foray as a "political stunt", as the Democratic hopeful got set to head to Europe and the Middle East.

As the Illinois senator's trip shaped up as a huge media event, McCain's Republican allies attempted to crank up the pressure on Obama, ahead of his high risk, high reward mission to meet foreign leaders.

Obama is also expected to visit war zones in Iraq and Afghanistan, though details have not been released for security reasons.

"As this trip becomes reality, it is also reality that it is more about politics than it is about fact-finding," Republican Senator Richard Burr told reporters in Washington.

Republican representative Eric Cantor, another high-profile McCain backer, complained that top network television anchors were set to travel to Europe to interview Obama, making the trip a huge media event back home.

"The question really needs to be posed, is this type of coverage fair? This is nothing but a political stunt," he said.

Earlier, McCain's spokeswoman Jill Hazelbacker signalled that the Arizona senator's team considered Obama fair game, even during trips to Iraq and Afghanistan.

"I found it interesting that he released his plans for the way forward in Iraq and Afghanistan prior to visiting the region or speaking to commanders on the ground," Hazelbacker said on Fox News.

"Let's stop the pretence this is a fact-finding trip, it is the first of its kind, campaign rally overseas."

The Obama campaign rejected the McCain supporters' central thrust that the Democratic hopeful had made up his mind in Iraq before holding talks with war commander General David Petraeus.

"All John McCain has ever looked for in Iraq are reasons to stay there indefinitely," said Obama spokesman Hari Sevugan.

"It is clear that he is going to continue to adhere to George Bush's ideological agenda even as every other critical national security challenge is neglected."

In a sweeping new national security blueprint, Obama this week announced plans to pull troops out of Iraq at the rate of one or two brigades a month, and to divert at least two combat brigades to Afghanistan.

The Obama team also took issue with Hazelbaker's comments, recalling that McCain had once suggested the two candidates travel to Iraq together.

Obama is expected to travel to Jordan, Israel, the West Bank, Germany, France and Britain next week.