Republican presidential candidate Mitt Romney pauses during a speech at a campaign event at Horizontal Wireline Services in Irwin.

Reno, Nevada - On the eve of a trip abroad, Republican presidential candidate Mitt Romney promised a robust foreign policy and accused President Barack Obama of weakness in the face of US adversaries.

“This is very simple: If you don't want America to be the strongest nation on Earth, I am not your president,” Romney told a convention of the Veterans of Foreign Wars. “You have that president today.”

Romney was cutting in his criticism of how Obama has dealt with Israel, accusing the president of neglect and “shabby treatment” of a key ally.

Although US voters remain focused on the economy, the war in Afghanistan, conflict in Syria and the growing influence of China make for a critical backdrop in the campaign for the November 6 election.

Often criticised by Democrats as lacking experience abroad, Romney, the former Massachusetts governor, travels to Britain, Israel and Poland this week to try to boost his foreign policy credentials.

The Republican blamed the White House for national security leaks to the media and assured war veterans that a Romney administration would keep a tight lid on secret information.

“What kind of White House would reveal classified material for political gain?” Romney said. “I'll tell you right now: Mine won't.”

He blasted Obama over the leaks, including those about the raid that killed al-Qaeda leader Osama bin Laden and cyber-warfare that has reportedly been used against Iran.

Attorney General Eric Holder last month appointed two chief federal prosecutors to spearhead an investigation into suspected leaks of classified information amid allegations the White House made the disclosures to boost Obama's re-election chances.

“This conduct is contemptible,” Romney said. “It betrays our national interest. It compromises our men and women in the field. And it demands a full and prompt investigation, with explanation and consequence,” Romney said. - Reuters