WASHINGTON (CNN) - Former Republican presidential candidate Mitt Romney took aim at President Obama's foreign and national security policy Monday, criticizing the commander-in-chief's message abroad as a "tour of apology" and calling plans to trim the missile defense budget a "grave miscalculation" that puts the nation at risk in the face of urgent threats like North Korea's nuclear ambitions.
"Arrogant, delusional tyrants can't be stopped by earnest words and furrowed brows," Romney told a conservative crowd at a speech sponsored by the Heritage Foundation in Washington. "Action - strong, bold action coming from a position of strength and determination - is the only effective deterrent."
Nearly two weeks after former Vice President Dick Cheney took on President Obama's national security policy, Romney delivered the latest in a string of tough critiques of the new administration - including a bruising take on Supreme Court pick Sonia Sotomayor - that have made the former Massachusetts governor a conservative favorite in the first months of the new administration, even as he carefully avoids the kind of incendiary attacks and media overexposure that could threaten mainstream appeal he'd need to reach the Oval Office.
Romney argued Monday that the defense budget had been short-changed, and the nation's military readiness has been endangered, because of the president's call to increase spending on domestic programs.
"None of that [new spending] was spent on increasing the defense modernization budget - a failure that history will never understand or excuse, in my view," he said.
The nation's military readiness, Romney argued, was also threatened by the overall economic decisions the president has made.
"At the most fundamental level, our military might depends on the long term strength of our economy," he said. "The president's planned budgets and multitrillion-dollar deficits, financed by a level of borrowing never before attempted by any nation in history, puts our whole economy in jeopardy."
Romney predicted the president's actions "may take us past that proverbial tipping point" and spark a crippling crisis of confidence in the dollar.
Romney, who ran the investment firm Bain Capital before entering politics, often touted his business and managerial experience as a presidential candidate. But he had limited experience with national security matters - a shortcoming that his rival John McCain eagerly highlighted during the primaries.
Since the 2008 election, Romney has re-emerged as a vocal critic of Obama's security agenda, and has made a series of public statements aimed at raising his profile in the foreign policy arena.
In April, he blasted Obama in The Weekly Standard for not objecting when Nicaraguan President Daniel Ortega criticized the United States at the summit of the Americas in Trinidad and Tobago.
"President Obama shrank from defending liberty here in the Americas," Romney wrote.
Last month, when Obama and Cheney presented dueling speeches on the use of enhanced interrogation techniques against suspected terrorists, Romney defended the former vice president and said that the president's speech "was more tortured than the enhanced interrogation techniques he decries."
Romney has said he will not hesitate to praise the president when he agrees with him. At an April fundraiser for Senate Republicans, for instance, Romney applauded Obama for taking the right steps in Iraq and Afghanistan. But despite those kind words, Romney has so far been more critical than supportive of the administration's foreign policy agenda.
A disciplined politician, Romney is quick to say he's not a presidential candidate. But his schedule seems to be a bit off-message.
Earlier this year, he got a hero's welcome at the Conservative Political Action Conference, where more than a few attendees insisted his economic credentials might have nabbed him the Oval Office if the economic crisis had hit before the Republican Party had decided on its standard-bearer.
On Friday, he was the keynote speaker at the Virginia GOP's Commonwealth Gala dinner in Richmond. On Sunday, he weighed in on his party's future on Fox News.
Romney is making appearances as a key member of the National Council for a New America - the move, led by House Minority Whip Eric Cantor of Virginia, to re-brand the GOP. Meanwhile, Free and Strong America PAC - Romney's political action committee dedicated to supporting conservative candidates - is helping him build the national network of party loyalists he'd need to clinch the nomination.
On Sunday, the 2008 presidential contender denied reports he was planning to move his permanent residence to New Hampshire in advance of a repeat run for the nation's top spot. But he was more equivocal on the overall question of a 2012 bid.
"I'm not going to close that door," he told Fox - although he added, "I'm not going to walk through it either."
"[T]he action that I'm going through right now is trying to help people who I think would make a difference for the country and, frankly, also help some people who helped me," he said.
Romney's reinvention hasn't come without a few false steps. Supporters of Newt Gingrich, another Republican leader whose name is regularly mentioned as a possible presidential candidate, complained last month that the former House Speaker was initially prevented from joining the NCNA by the former governor's team - a charge that Romney's aides, and Cantor representatives, strongly denied.
And after he weighed in on behalf of New Jersey gubernatorial candidate Chris Christie, supported by the Free and Strong America PAC, Christie's primary rival Steve Lonegan fired back with a salvo aimed squarely at Romney's chief vulnerability last cycle: the sense by some movement conservatives that the Massachusetts resident was more moderate than he would like Republicans to believe.
"Mitt Romney was rejected by Republican Primary voters because he was a moderate trying to pass himself off as a conservative just in time to win an election," Lonegan said in a statement released by his campaign.
It's the kind of reaction that helped cost him the nomination last cycle - and the sort of response his team would like to banish long before the next race takes shape. But Romney's not counting on immediate rewards on his long journey back to the campaign trail.
"We have plenty of time to decide what the future holds," he told Fox on Sunday. "It's very early, five months into the president's term. We'll see how he does, and we as a party are going to come back stronger, more vibrant, and more committed to following the principles that have always been at the base of our party."