RENO, Nev. — Their goodwill moment gone, President Barack Obama and challenger Mitt Romney plunged back into their acrimonious political campaign on Monday, Obama doubting Romney's readiness to be commander in chief, Romney accusing the president's team of offering "almost all attack ads."

Days after the Colorado movie massacre brought reflection and talk of national unity from both camps, the fight was on again.

Foreign affairs made a rare move to the fore of the campaign as Republican Romney, the former Massachusetts governor, readied for a closely watched trip overseas. Obama, meanwhile, 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 Romney's travels before they began.

Both White House contenders are trying to gain the military vote. In the 2008 election, 54 percent of those who said they had served in the military voted for Sen. John McCain, himself a veteran, to 44 percent for Obama, according to exit polls.

More broadly, both sides ended what had been a weekend of political truce in deference to grieving families and victims of the shooting. Obama and Romney returned to raising millions of dollars and taking jabs at each other over jobs, leadership and security.

Both saw little time to waste in a tight, bruising race – and saw little need to apologize for any tactics.

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 for England, Israel and Poland.

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 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 eased back into his criticism of Romney throughout the day. He made veiled attacks against Romney at both the VFW speech and a high-dollar fundraiser in Oakland, Calif., without mentioning the presumptive Republican nominee by name.

But by Monday night, the president grew more direct in his attacks. During a speech to about 1,000 people at a raucous fundraiser in Oakland, Obama said Romney 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 shot back, saying Romney was distorting his words and going "a little over the edge" in his political attacks.

The president began all of his events Monday by recalling his emotional meetings with the families of the Colorado shooting victims. At an intimate, $35,800 per person dinner in Oakland, Obama said the families and shooting survivors "would make you extraordinarily optimistic about America."

Among the donors at the dinner 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.

Obama's California fundraisers and four more money events in Oregon and Washington on Tuesday were expected to bring in more than $6 million for his campaign.

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.

The Obama campaign on Monday released a new television advertisement casting the election as a choice between two contrasting economic visions.

"Sometimes politics can seem very small. But the choice you face, it couldn't be bigger," Obama said in the ad, which was to air in nine battleground states.

___

Beaumont reported from Irvine, Calif. Associated Press writers Ben Feller and Mark S. Smith in Washington, Matt Sedensky in Manalapan, Fla., and Sandra Chereb in Reno, Nev., contributed to this report.

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