PARADISE VALLEY, AZ -- Former Massachusetts Governor Mitt Romney said Tuesday that he's turning to the "closing arguments of his campaign," and that the time for collecting checks and campaigning selectively was nearly over.

Romney signaled that his campaign was moving into a new phase to win over skeptical GOP primary voters with just less than a month to go until the first votes are cast.

"We’re just starting. We’re just getting up with ads. We’re making our closing argument," Romney said at a campaign stop here in the Phoenix suburbs. "You’ll see me campaigning aggressively. I’ve still got I think about seven more days of fundraising and then we get to spend almost all of our time in New Hampshire, Iowa, South Carolina, Florida -- a couple of other states."

Romney, who has run a campaign largely sheltered from the media glare also said Americans would be seeing a lot more of him on their televisions.

"I’ll be on the air a good deal more than in the past, doing our very best to communicate to the American people why I’m running for president and hopefully getting their support," Romney said. Earlier today, Fox News announced Romney would be a guest on Fox News Sunday, his first appearance on a Sunday show this year.

Romney's remarks came on a day in which two new polls showed him trailing former House Speaker Newt Gingrich by double digits in Iowa, whose first-in-the-nation caucuses loom four weeks away. Romney predicted that the nomination battle, which is now seen by many political analysts as a two-man contest between Gingrich and himself. would be a long one.

"I know the beginning will be what, January 3rd, but this will probably take longer than a week or two to sort out," Romney said. "My expectation is this campaign that’s going to go on for a while and I expect to win it. I need to get something over 1,000 delegates and we're just getting started. I'm pleased with where we are right now, and anticipate getting the nomination if I do my job right."

Doing that job right will involve not just raising money, which Romney has done better than any candidate in the race -- including at a lunch fundraiser here an attendee described as filled to capacity -- but also creating contrasts with Gingrich, something Romney told FOX in an interview at the event site he would be willing to do.

"We're going to make sure that the differences in our experience and perspective are well-aired. You can be sure I will not be quiet, I am going to make sure my message is heard loud and clear," Romney told FOX. "Gingrich is a friend, I respect him, but we have very different life experiences. If Americans want someone whose been in Washington the last 40 years, then that's him but if they want someone whose outside of Washington and a freedom-based society...that kind of experience is I think what it takes. America needs a leader, not so much an insider, but a leader to get America going again."

Former Vice President Dan Quayle, who appeared at Romney's side today to offer his endorsement, sounded a similar note, describing Romney as an outsider, conservatives "best hope for the future," and someone uniquely suited to take on the challenges of Washington.

Yesterday in New York, Gingrich looked to derail Romney's outsider narrative by highlighting, as Democrats have done for months, Romney's two unsuccessful past runs for office, saying "I don't know if that makes [Romney] a career politician. I'll let you decide."

Today, Romney fired back at Gingrich.

"I ran for office but I didn't win. That doesn't mean I spent my time in Washington, because I didn't win. Had I won, why we wouldn't be having this argument, I would be president of the United States," Romney said. "Instead, when I lost elections I got to go back and be a businessman again and allowed me to be involved in the economy and to understand that the grass roots level what American people are suffering and what I can do to get jobs again."

Former Vice President Dan Quayle will endorse Mitt Romney for president tomorrow at a campaign event in Arizona.

The endorsement will take place in Paradise Valley, Arizona, which is located within the congressional district of Ben Quayle, the former Vice President's son, who was elected to the House in 2010 and has yet to make an endorsement in the presidential race.

Quayle, who was vice president under President George H. W. Bush, represented Indiana in the House of Representatives for two terms, and also served in the senate. He has reportedly remained active in Republican fundraising circles, particularly in Arizona, where he has a home.

Romney met with former President Bush at the latter's Houston home last week. The meeting was described by aides to Romney as a chat between friends; Bush did not offer his endorsement.