Reno, Nevada: President Barack Obama raised doubts about challenger Mitt Romney’s foreign policy credentials Monday as the candidates plunged back into their acrimonious political campaign with international affairs making a rare move to the fore.

The focus on foreign affairs came as Romney readied for a closely watched trip overseas. Obama told a military audience that he was the only one in the race with a record, not just words, on international matters as he sought to undercut the Republican’s travels before they began.

Romney, who will set out this week for England, Israel and Poland, accused Obama of focusing on negative attacks and failing to offer a “healthy, important debate” on America’s problems.

Both sides saw little time to waste in a tight, bruising race — and saw little need to apologise for any tactics.

Obama and Romney are both trying to gain the military vote. In the 2008 election, 54 per cent of those who said they had served in the military voted for Senator John McCain, himself a veteran, to 44 per cent for Obama, according to exit polls.

A positive campaign “really would be nice,” Romney said even as he declared that sentiment over in an interview with CNBC. He blamed Obama for the tenor.

Obama told the Veterans of Foreign Wars he has kept his promises to end the war in Iraq, wind down the conflict in Afghanistan and go after Al Qaida leader Osama bin Laden wherever he was hiding. The terrorist mastermind was killed in a raid on Obama’s orders.

In every example, Obama poked at Romney without naming him. On Iraq, Obama suggested Romney would have kept forces in the war zone indefinitely.

“When you’re commander in chief, you owe the troops a plan,” Obama said. On Afghanistan, Obama needled Romney for opposing the 2014 timeline for ending the war. “You know what? That’s not a plan for America’s security,” he said.

Romney was to get his say before the VFW, too, on Tuesday before setting out overseas.

Trying to set the expectations for the opponent, Obama campaign officials challenged Romney to offer clear policy ideas during his three-country trip. Romney’s travels will be viewed as a measure of how well he can stand up on the world stage. Obama took an even broader such trip as a candidate in 2008.

Four years later, Obama said on Monday: “We’re leading around the world. There’s more confidence in our leadership. We see it everywhere we go.”

A Romney spokesman, Ryan Williams, countered that Obama had “diminished our moral authority” in the world.

Still in the shadow of the Colorado rampage, both campaigns weighed how to calibrate their tones.

Obama spokeswoman Jen Psaki said the president was moved by his visits Sunday with survivors and family members of the victims of Friday’s mass shooting outside Denver. Still, she said: “We’ve got a long way to go here. ... [Obama] knows that he needs to make sure people know what’s at stake.”

Romney noted that Obama aide David Axelrod had begun the day reminding via Twitter of the campaign’s request to see more of Romney’s tax returns.

“I haven’t seen the healthy, important debate coming from the president’s team,” Romney said. “It’s been almost all attack ads on all sorts of peripheral issues.”

Romney himself was back at the rhetorical attack, telling donors in California that Obama was “out of ideas and out of excuses.”

The pursuit of money kept on rolling, too.

In California, Romney raised $10 million over two days.

Obama moved on to California for a night of fundraisers” Oregon and Washington state were next on Tuesday. He was expected to raise more than $6 million.

The president opened remarks to donors at an intimate, $35,800 per person dinner in Oakland by recounting his meetings with those impacted by the Colorado shooting. The spirit of the community, Obama said, “would make you extraordinarily optimistic about America.”

Both campaigns were keeping their largely negative television advertisements off the air in Colorado, a key battleground state in the November election. Vice President Joe Biden, campaigning for his boss in Florida, jettisoned his typical speech to focus on the shooting victims and the stories of heroism from that night.