Romney was to level his accusation Tuesday afternoon during an address to the Veterans of Foreign Wars convention, his strongest indictment of Obama's foreign policy yet in a close race in which the Republican has largely focused on the nation's sluggish economy.
"This conduct is contemptible. It betrays our national interest. It compromises our men and women in the field," Romney says, according to excerpts his campaign released before the speech. "And it demands a full and prompt investigation, with explanation and consequence."
In moving away from his preferred issue, the economy, Romney was venturing further into national security policy, a realm usually viewed as the home turf of the incumbent.
But by alleging that the Obama administration divulged to reporters on multiple occasions details of secret missions, Romney was suggesting that Obama lacks the discipline for the office.
The former Massachusetts governor's speech to the veterans group also was a stinging retort to Obama's speech to the same group Monday.
Obama sought to raise the stakes for Romney's speech with remarks Monday at the VFW convention, casting himself as a steady commander in chief tested by two wars and the successful raid on Osama bin Laden's compound. The president was continuing a Western campaign swing with appearances Tuesday in Oregon and Washington.
While raising money in California on Monday, Romney offered a preview of his latest critique of Obama, telling about 400 supporters at a hotel in Irvine that "the consequence of American weakness is seen around us in the world."
However, Obama touted his record as one of promises kept: End the war in Iraq, wind down the conflict in Afghanistan and go after the al-Qaida leader behind the 9/11 attacks.
Without naming Romney, Obama indirectly suggested his opponent would have kept troops in Iraq indefinitely and criticized him for opposing the president's 2014 timeline for withdrawal from Afghanistan.
"That's not a plan for America's security," Obama told the veterans group.
Although Obama suggested that Romney was an inexperienced critic working to polish his own credentials, Romney appeared ready to turn from his chief argument that Obama is a failed steward of the economy and criticize the president on foreign and national security policy.
Romney noted Sunday that key ally Australia's foreign minister, Bob Carr, had told him during a private meeting that the United States was "in decline." However, Carr on Monday clarified his remarks, saying he wasn't criticizing the U.S. when he spoke of a nation "in decline." Kim Beazley, Australia's ambassador to the United States, said Carr's remarks "represent a considered assessment of the U.S. economy and an antidote to talk of U.S. declinism."
Romney also suggested Monday that the Obama administration had not been aggressive enough in deterring Iran's nuclear ambitions or in trying to quell the violence in Syria. Romney said he agreed with Obama's call for Syrian President Bashar Assad's departure but said Obama had not shown proper leadership to force it.
"I think from the very beginning we misread the setting in Syria," Romney told CNBC. "America should've come out very aggressively from the very beginning and said Assad must go. ... The world looks for American leadership and American strength."
The Obama administration has long called for Assad to leave Syria, relying on a strategy of sanctions and international isolation to pressure Assad into handing over power. ,
The shift toward world affairs precedes Romney's trip, beginning Tuesday, to Britain, Israel and Poland. It also comes as the campaigns' aggressive tone resumed after a three-day hiatus after the deadly shooting at a Colorado movie theater Friday.
During a speech Monday night to about 1,000 people at a raucous fundraiser in Oakland, Calif., Obama said the presumptive GOP nominee was "knowingly twisting my words around to suggest I don't value small business."
Romney had revived his attacks Monday on Obama's comment this month that government is due a share of the credit for business success. The president said Romney was distorting his words and going "a little over the edge" in his political attacks.
While the weekend truce was fleeting, the Colorado tragedy did not keep either candidate from chasing campaign contributions.
Romney headlined fundraisers over two days in California, netting $10 million.
Obama was expected to raise more than $6 million during two days of West Coast fundraising. He headlined three events in the San Francisco Bay area Monday and was to attend four more Tuesday in Seattle and Portland, Ore.
Among the donors at a $35,800-per-person dinner in Oakland, Calif., were two people connected to Solyndra, a failed California solar energy company that has been part of Romney's attacks on Obama. Solyndra was the first renewable energy company to receive a federal grant under Obama's 2009 stimulus law but went bankrupt last year, leaving taxpayers on the hook for more than $500 million.
Steve Westly, a Silicon Valley venture capitalist who warned the White House about Solyndra's shaky finances, and Matt Rogers, a former Energy Department official who was part of the Solyndra loan guarantee process, were among the 60 people in attendance at the private home.
Associated Press writer Julie Pace in San Francisco contributed to this report.