Mitt Romney rejected claims by President Barack Obama that he would sign off on more tax breaks for the wealthy if elected president, but again declined to offer specifics on how exactly he would accomplish his goal of lowering taxes for other Americans while also balancing the budget.

In an interview with NBC's "Meet the Press," Romney said he would offset his proposed 20 percent tax cut for all Americans by eliminating loopholes and deductions for high-income earners. He argued that his plan would in effect lower taxes for middle-class Americans while keeping tax rates the same for wealthy Americans.

"People at the high end, high-income taxpayers, are going to have fewer deductions and exemptions. Those numbers are going to come down. Otherwise they'd get a tax break," Romney told NBC. "And I want to make sure people understand, despite what the Democrats said at their convention, I am not reducing taxes on high-income taxpayers."

Romney argued that limiting deductions and exceptions would keep government revenues up and "encourage more hiring" and "encourage growth" in the economy. He said he wants to make "sure we don't put any bigger burden on middle-income people."

But asked about "the specifics of how you get into this math," Romney declined to offer any additional details, suggesting the "principles" of his plan should be enough for Americans to judge his tax proposals.

"The specifics are these, which is those principles I described, are the heart of my policy," Romney 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 Republican presidential nominee criticized GOP lawmakers in Congress—a group that includes his running mate, Rep. Paul Ryan—for backing automatic budget cuts during debt negotiations last year. Under the agreement signed by the White House and the Republican Congress, the automatic cuts, known in Washington as "sequestration," will automatically remove $1.2 trillion from the budget unless lawmakers can find other cuts to replace them. At least half the cuts are coming in defense spending, which Romney called an "extraordinary miscalculation" on Obama's part and a "big mistake" for Republicans to agree to it.

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"I thought it was a mistake on the part of the White House to propose it. I think it was a mistake for Republicans to go along with it," Romney said.

Asked if he would be willing to "cut a deal" in order to keep the country away from a "fiscal cliff," Romney indicated it's "critical to get the country back on track." He did not say how far he would go in working with Democrats.

"There's nothing wrong with the term 'compromise,' but there is something very wrong with the term 'abandoning one's principles,'" Romney said. "And I'm going to stand by my principles. And those are I am not going to raise taxes on the American people. Our problem in our country is not that we're not paying enough taxes. It's that we're spending too much money and the economy is not growing as it could and should."

On Obama's health care law, Romney reiterated that he would repeal the law, if elected, but would replace it with his own measure that would include some of the elements from Obama's law, including coverage for those with "preexisting conditions." He said he also would keep rules that allow young people to stay on their parents' health care plans.

"I say we're going to replace Obamacare. And I'm replacing it with my own plan. And even in Massachusetts when I was governor, our plan there deals with preexisting conditions and with young people," 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 health care reform that I'm going to put in place."

While polls show he received no "bounce" in the aftermath of the Republican National Convention, Romney still argued that he's in a "better spot" because voters were able to become more aware of his personal story and his policies.

"I think we're making real progress," Romney said. "People go to see Ann and hear our story. And the result of that is I'm better known, for better or for worse. And that allows me to continue to hammer away on what I do to get America on the right track. And I have really two months to be able to convince people I can do a better job than the incumbent. I think I can do that. So I'm in a better spot than I was before the convention."

Romney seized on Friday's disappointing jobs report as proof that he has a good chance of defeating Obama in November.

"I think it's tough to beat an incumbent if the incumbent's record is good," Romney said. "I think this incumbent has a very challenged record. … This president has not been able to deliver on his promises. People are dissatisfied with where he's taken the country. And that gives me an opportunity, which might not have been available had he done what he said he would do."

Asked if he would be willing to endanger himself politically to the point of becoming "a one-term president," Romney said he "could not care less about his political prospects."

"I want to become president of the United States to get this country on the right track again. America is at a critical crossroads," the GOP candidate said. "We've got to put Americans back to work. And politics, whether I'm highly favored, not highly favored, just doesn't enter into the equation."