Regional heavyweight Saudi Arabia is to host talks on Thursday between Kerry and ministers from 10 Arab states and Turkey on joint action against the Islamic State (IS) group.
The talks coincide with a much-touted address from President Barack Obama at the White House, where he will outline a strategy to confront IS and address criticism that he has been slow to respond to a wave of atrocities that has shocked the world.
Britain also announced on Tuesday that it will ship $2.6 million worth of weapons to Kurdish forces in Iraq, to help roll back the militants' lightening advances.
Kerry's expected arrival in the region on Wednesday comes as Washington hailed the formation of the new government in Baghdad, which has been billed as more inclusive.
Iraq's campaign to claw back territory it lost in the Sunni Arab heartland north and west of Baghdad in June, and US efforts to engage Sunni governments in the fightback, have been complicated by regional sectarian politics.
Saudi Arabia and the five other Gulf Arab states have had deeply strained relations with the Shia-led government in Baghdad, with each side blaming the other for the militants' gains.
But their foreign ministers will be among those attending Thursday's talks in the Saudi city of Jeddah, along with top diplomats from Egypt, Jordan, Lebanon, Turkey and Iraq itself.
They will address "terrorism in the region, extremist organisations behind it and means of fighting them," Saudi state media said.
The Arab League, which has stopped short of explicitly backing ongoing US air strikes against IS, also drummed up regional support for the fight.
Ahead of his visit, Kerry vowed to build "the broadest possible coalition of partners around the globe to confront, degrade and ultimately defeat (IS).
"Almost every single country has a role to play in eliminating the (IS) threat and the evil that it represents," he said.
Notably absent from Jeddah will be the Syrian government - facing a three-and-a-half-year uprising backed by many of the participants - and its regional ally Iran.
IS has taken advantage of the conflict to seize a big chunk of northeastern Syria in fighting with government forces, rival rebel groups and Kurdish militia.
Damascus views itself as a bulwark against the militants, but Washington has ruled out any cooperation for fear of alienating Syria's Sunni majority, who largely support the uprising.
Washington launched air strikes against militants in Iraq on August 8.
Obama has so far held back from authorising strikes on IS in Syria but has promised to outline a comprehensive strategy against the group on both sides of the border in a speech to the American people Wednesday.
An opinion poll published on Tuesday suggested Americans are hawkish towards IS, with nearly three-quarters favouring ongoing air strikes against the group in Iraq while 65 percent would approve extending operations into Syria.
The Pentagon said on Tuesday that more strikes had been carried out over the previous two days near western Iraq's massive Haditha dam as part of operations to defend it from IS forces.
After months of wrangling, Iraq's new Prime Minister Haidar al Abadi finally formed a government on Monday that Washington said had "the potential to unite all of Iraq's diverse communities".
Kerry described the new government as a "major milestone" in efforts to woo the Sunni Arab minority away from IS after the divisive rule of Abadi's predecessor, Nuri al Maliki.
Shia Iran - alongside the United States, the key outside power in Iraq - said it hoped the change of government in Baghdad would help turn the tide against IS.
"I hope that during your new mandate, complete calm will return to your country," President Hassan Rouhani said.
In reality, the new government does not constitute quite the sea-change hailed by Washington.
It remains dominated by Iraq's Shiite Arab majority. The Kurds hold fewer ministries than before and the Sunni Arabs relatively minor ones, while the divisive Maliki becomes one of three vice presidents.
In other developments, French President Francois Hollande will visit Iraq on Friday ahead of hosting a conference in Paris on security in the country next Monday, his office said.
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