The Republican presidential nominee talks with NBC's David Gregory about his policy positions and his standing in the 2012 race.

Mitt Romney argued Sunday that voters should have enough of a sense of his principles to have confidence in how he'd handle the nitty-gritty details of taxes, spending and health care as president.

The Republican presidential nominee, appearing on NBC's "Meet the Press," argued his plan to cut taxes squares with his vow to achieve a balanced budget by the end of a second hypothetical term, even though achieving those two goals would seem difficult, if not incongruent.

"My tax policy is designed to find a way to encourage more hiring in this country. I'm very concerned that we have 23 million people that are out of work or stopped looking for work or under-employed," Romney told moderator David Gregory. "So everything I want to do with regards to taxation follows simple principles, which is bring our rates down to encourage growth, keep revenue up by limiting deductions and exemptions and make sure we don't put any bigger burden on middle income people. In fact, I want to lower the burden on middle income people."

But Romney has been dogged by criticism that his plan lacks specifics, thereby making it difficult to conceive of how he would be able to reasonably achieve his agenda.

Romney's tax plan calls for making a 20 percent, across-the-board cut to marginal tax rates while keeping most existing taxes on investment the same (and cutting investment taxes altogether for households earning less than $200,000.) The former Massachusetts governor has argued that if "we limit or eliminate some of the loopholes and deductions at the high end," he could maintain current levels of tax revenue while also stimulating growth.

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But, pressed for specifics, Romney resisted, and said his "principles" make up the details of his policy.

"The specifics are these, which is those principles I described are the heart of my policy," he said. "And I've indicated as well that — contrary to what the Democrats are saying — I'm not going to increase the tax burden on middle income families. It would absolutely be wrong to do that."

The opacity of some of Romney's proposals has invited plenty of scrutiny from Democrats, including President Barack Obama, who seized upon Romney's tax proposals in his convention speech on Thursday.

"When Gov. Romney and his friends in Congress tell us we can somehow lower our deficits by spending trillions more on new tax breaks for the wealthy, well — what'd Bill Clinton call it? You do the arithmetic. You do the math," the president said in Charlotte.

Brian Snyder / Reuters Republican presidential candidate and former Massachusetts Governor Mitt Romney talks briefly with reporters after stopping to buy two pizzas at Lui-Lui restaurant in West Lebanon, New Hampshire September 5, 2012.

Romney shot back Sunday: "I want to make sure people understand, despite what the Democrats said at their convention, I am not reducing taxes on high income taxpayers."

Speaking of those conventions, Romney said he has emerged in a "better spot" for his campaign by spending a week better familiarizing voters with his personality and record. And the GOP nominee pounced on Friday's anemic jobs report as further evidence as to why voters should back him.

"It is a jobless recovery, if it's a recovery at all," Romney said of the pace of the recovery. "If President Obama is re-elected you're not going to see our unemployment picture change dramatically. You're not going to see us create the jobs we need to create or the rising incomes people need."

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The economy joins the issues of taxes and spending as top problems a President Romney would be forced to confront almost immediately upon taking office. Current tax rates will automatically spring upward at the beginning of 2013 absent another extension of the so-called "Bush tax cuts," or some other kind of substitute comprehensive tax reform. And a series of automatic spending cuts stipulated by the 2011 debt ceiling deal will take place in January unless Congress makes steps to undo them.

Those looming issues are linked in large part to partisan discord in Congress, a phenomenon that might not be broken with this year's elections. Internal divisions within the GOP, pitting conservatives who have pushed for deeper cuts against their party's leadership, have additionally complicated dealmaking on Capitol Hill.

As president, Romney said he would seek out compromise, but not in such a way that it would contravene his principles.

"There's nothing wrong with the term compromise, but there is something very wrong with the term abandoning one's principles," he said. "And I'm going to stand by my principles. And those are I am not going to raise taxes on the American people."

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Those governing principles extend to health care, a hot-button issue this election which Romney has vowed to tackle if elected.

The GOP nominee has vowed, for instance, to repeal Obama's signature health care law and replace it with his own series of reforms. But that doesn't mean that some of the more popular elements of "Obamacare" would necessarily go away, Romney said.

"I'm not getting rid of all of health care reform. Of course there are a number of things that I like in healthcare reform that I'm going to put in place," said Romney. "One is to make sure that those with pre-existing conditions can get coverage. Two is to assure that the marketplace allows for individuals to have policies that cover their family up to whatever age they might like. I also want individuals to be able to buy insurance, health insurance, on their own as opposed to only being able to get it on a tax advantage basis through their company."

Romney also spoke to the issue of foreign policy, a topic on which he scarcely touched at his convention speech in Tampa. Romney said that Obama has "had some successes and he's had some failure," an example of the latter being the president's handling of Iran.

"President Obama had a policy of engagement with Ahmadinejad. That policy has not worked and we're closer to a nuclear weapon as a result of that," he said.

Romney said he would handle it differently by more aggressively pursuing diplomacy and sanctions, while also maintaining a military option.

"We need to use every resource we have to dissuade them from their nuclear path. But that doesn't mean that we would take off the table our military option. That's something which certainly every American would hope we would never have to use," Romney said. "But we have to maintain it on the table or Iran will, undoubtedly, continue their treacherous course."