Bush, in a major speech at the non-profit National Endowment for Democracy, will also call for greater political openness in places like Burma and China, White House national security adviser Condoleezza Rice said Wednesday.
But he will focus on the Middle East, "the region that has been most deprived of freedom," arguing that Saddam Hussein's ouster has given the entire region fresh opportunity to embrace democratic change, she said.
It was unclear whether Bush, who has called for the eventual creation of a Palestinian state living at peace with Israel, would mention the stalled Middle East peace process.
"He will talk about the need to press forward toward democratic change, recognizing that no region and no people should be isolated from the great benefits that freedom and democratic development can bring," said Rice.
Bush will also acknowledge that some 60 years of US support for regimes in the Middle East "that were not devoted to political liberty for their people" fed widespread anti-American sentiment that fuels terrorism, she said.
"We found that we did not buy security and stability but rather frustration and pent-up emotions and a region that has fallen behind in terms of prosperity and in fact continues to produce ideologies of hatred," she said.
Bush will stress that spreading global freedom is "inextricably linked" to US security, a theme he has sounded since the September 11, 2001 terrorist attacks, Rice told a small group of reporters in a preview of the speech.
Asked whether the speech heralded greater US involvement in the region, Rice replied: "It certainly signals that the United States is going to associate itself with those who believe that the future is freedom."
Bush will specifically praise democratic progress in Bahrain and Jordan "in fact, even in Saudi (Arabia), where you're beginning to some stirrings of the need for a political voice for the people," said Rice.
In China, "economic liberty gives an opportunity for the march of political liberty, but where there needs to be a commitment to making that link," said the adviser, who added that Egypt would also be mentioned by name.
In the run-up to the war in Iraq, the US leader and his top aides said that putting that country on track for prosperity and democracy would have a domino effect that could lead to the spread of political and economic freedom throughout the Middle East.
Mindful of regional sensitivities, Rice stressed that Bush was not pushing for a "one-size-fits-all approach" and that embracing democracy did not necessarily mean embracing US values.
"Modernization, in the sense of political and economic freedom, isn't synonymous with Westernization," she said. "Freedom will have to find its own voice with the traditions of the region."
She also emphasized that Bush was embracing local movements, not imposing a set of values on the region, and said he was not calling for "results tomorrow" but "talking about the important transition that is underway."
"You could never, as the United States, decide, 'all right, this region now needs to pursue freedom.' But the people of the region are clamoring for it," she said.
Rice likened Bush's speech to former president Ronald Reagan's denunciation of the Soviet Union in what has come to be known as his "evil empire" speech, a June 1982 address to the British House of Commons.
In that address, Reagan sought to hearten dissidents and pro-democracy activists in Soviet bloc countries by stating Washington's unequivocal alliance with their cause.