Mitt Romney, trying just days before Michigan's crucial Republican presidential primary to establish himself as the candidate best prepared to turn around the economy, Wednesday unveiled a detailed plan for recovery that cuts taxes dramatically.

 The cornerstone of the plan is to impose a permanent across the board 20 percent cut in marginal income tax rates. That would return the current top rate, now 35 percent, to 28 percent. He reiterated an earlier campaign pledge that families with annual incomes of less than $200,000 would pay no taxes on income from capital gains, interest and certain dividends.

Such rates, he said Wednesday, will "create powerful incentives for Americans to save and invest, while spurring business investment and economic growth."

 Among Romney's other ideas:

 --Eliminating the estate, or death, tax.

 --Repealing the alternative minimum tax.

 --Cut the corporate tax rate to 25 percent. --Make the research and development tax credit permanent.

Part of how Romney would pay for these changes are dramatic cuts in federal spending. He has proposed reducing spending to 20 percent of Gross Domestic Product, down from the current 24 percent, by 2016.

 He says he'll save $500 billion with such steps, which would include a repeal of the 2010 federal health care law and allowing stetes to decide how to use federal money for several p rograms, notably Medicaid, the health program for low income and some disabled people.

 He provides few details about Social Security and Medicare changes, saying that he would "gradually raise the retirement age" and index the growth in benefits for higher-income beneficiaries to inflation, rather than wages. And he repeated an earlier pledge to set up a "premium support system" for younger workers, where they could choose among competing private plans for their senior care.

Mitt Romney and Rick Santorum are in a virtual tie in Michigan, site of the Feb. 28 Republican presidential primary, according to a new NBC News/Marist poll.

Romney, the former Massachusetts governor who grew up in the Detroit area, had 37 percent. Santorum, the former U.S. senator from Pennsylvania, trailed with 35 percent. Texas Rep. Ron Paul had 13 percent, while former House Speaker Newt Gingrich had 8 percent.

The candidates debate tonight in Arizona, site of another Feb. 28 primary, starting at 8 P.M. EST. The NBC/Marist poll showed Romney with a wide lead in Arizona.

Michigan is considered a key battleground, since a home state loss would be an embarrassment for Romney.The poll found him benefitting from a perception he is the best GOP bet to beat President Barack Obama in the fall.

Marist found that 51 percent thought Romney had the best chance to win; only 24 percent thought Santorum had the best chance. And 52 percent of those polled said that characteristic was the most important factor in their vote.

The poll was conducted Feb. 19-20. 715 likely GOP voters were surveyed. Margin of error is plus or minus 3.7 percentage points.

Mitt Romney kicked off what's likely to be lively week of campaigning with a fresh blast at Rick Santorum. Romney is pushing hard to win the Feb. 28 Michigan presidential primary.

Polls show Santorum, the former U.S. senator from Pennsylvania, leading. Romney grew up in the Detroit area; his father was governor of Michigan from 1963 to 1969.

Romney and his supporters went negative in Florida and buried Newt Gingrich, the former House speaker. Monday, Romney's camp tore into Santorum.

“Mitt Romney spent his career in the private sector as a chief executive, where he helped create jobs and turn around major enterprises. Congressman/Senator Rick Santorum, on the other hand, has spent his career in Washington. Rick Santorum is part of the problem, so he can’t be part of the solution," said spokeswoman Andrea Saul.

Her comments were accompanied by a long statement about Santorum's time in Washington--two terms as a House member, two as a U.S. senator.

Romney was governor of Massachusetts from 2003 to 2007, and tried to win a U.S. Senate seat. He lost a bid for a Massachusetts seat in 1994 to Sen. Edward Kennedy.

Former New Hampshire Gov. John Sununu, a Mitt Romney supporter, blasted Rick Santorum Friday for backing earmarks, or local projects lawmakers insert into spending bills.

"Senator Santorum is a nice man. I’ve known him for a long time. He’s a good friend," Sununu told reporters in a conference call arranged by the Romney campaign.

"But frankly when he got to Washington, he got very Washingtonian," said Sununu of the former Pennsylvania senator.

"He fell in love with earmarks to the point where he is willing to say he was proud of being part of the earmark gang. And that increase in spending is a very serious problem," he said.

Santorum has said he backed earmarks because they helped the state he represented. He and Romney, the former governor of Massachusetts, are battling to win Michigan's Feb. 28 presidential primary.

Ohio Attorney General Mike DeWine switched his support Friday from Mitt Romney to Rick Santorum.

"To be elected President, you have to do more than tear down your opponents," DeWine said in an announcement on the steps of the Ohio Statehouse in Columbus.

"You have to give the American people a reason to vote for you -- a reason to hope -- a reason to believe that under your leadership, America will be better.  Rick Santorum has done that.  Sadly, Governor Romney has not."

DeWine served with Santorum, a former Pennsylvania senator, in the U.S.  Senate

Romney and his supporters bombared Florida with negative ads, hoping to defeat former House Speaker Newt Gingrich. The Romney campaign lately has been criticizing Santorum for his spending record. Santorum leads Romney in polls in Michigan, site of a crucial Feb. 28 presidential primary. Ohio voters go to the polls a week later.

Mitt Romney, under suspicion by many conservatives because of his past as a center-right governor and political candidate, tried to make himself clear Friday:

"I know conservatism because I have lived conservatism."

The former Massachusetts governor got a good response from the crowd at the Conservative Political Action Conference, a three day convention of activists.

Here's how Romney explained his conservatism:

"I was raised in a home shaped by and rooted in conservative values. My mother’s father – my grandfather – came to America from England.  As a teenager, he was alone in a new country, but he risked it all for a chance at religious liberty and economic opportunity.

"You’ve probably heard how proud I am of my father.  He was born to American parents living in Mexico.  When he was five, they moved back to the United States.  His dad was a builder who went bust more than once.  My Dad grew up poor and never had a chance to finish his college degree.  But he believed in a country where the circumstances of one’s birth were not a barrier to achievement.  And with hard work, he became the head of a car company and the Governor of the great state of Michigan.

"The values that allowed my parents to achieve their dreams are the same values they instilled in my siblings and me.  Those aren’t values I just talk about; they are values that I live every day.  My 42-year marriage to my wife, Ann; the life we’ve built with our five sons; and the faith that sustains us – these conservative constants have shaped my life.

"In business, if you’re not fiscally conservative, you’re bankrupt.  I spent 25 years balancing budgets, eliminating waste, and keeping as far away from government as was humanly possible. I did things conservatism is designed for – I started new businesses and turned around broken ones. And I am not ashamed to say that I was very successful at it."

An hour before former Pennsylvania Sen. Rick Santorum was to speak to the Conservative Political Action Conference in Washington, Mitt Romney released a blast at his rival.

"tSenator Santorum now decries the obscene growth in federal spending and our national debt, but he was in Washington as this fiscal crisis grew – supporting billions in earmarks, repeatedly voting to raise the debt ceiling, and admitting that deficits no longer bothered him," Romney spokesman Andrea Saul said in a memo to media.

"Americans want a president who can offer solutions, not a lifelong politician who was part of the problem in the first place."

The Romney camp then recalls statements Santorum has made supporting earmarks, or local projects lawmakers routinely insert into spending legislation. Santorum has explained that was part of his job.

Santorum is popular among conservatives; Romney, less so. Both are to speak to the conference Friday.

Mitt Romney could be in for a rough night Tuesday, as polls suggest former Pennsylvania Sen. Rick Santorum has a chance to win the Minnesota caucuses.

Romney's camp put out a memo Tuesday morning that looks ahead, and perhaps tries to lessen the impact of the Tuesday result.

"It is difficult to see what (former Massachusetts) Governor Romney’s opponents can do to change the dynamics of the race in February," said political director Rich Beeson in the memo. "No delegates will be awarded on February 7 -- Colorado and Minnesota hold caucuses with nonbinding preference polls, and the Missouri primary is purely a beauty contest.

"Except for the Maine and Wyoming nonbinding caucuses running through February, the next contests are on February 28 in states where Governor Romney is strong. Arizona’s 29 delegates will be bound in a winner-take-all contest. Michigan, the state where Governor Romney grew up, binds 30 delegates"

Beeson then looked ahead to March, with optimism.

"The rules for the March states offer even less comfort to Governor Romney’s opponents. With so many states and territories voting, organization and resources are key. Ours is the only campaign to be active in all of these states, and we have the resources and organization to maximize delegate totals according to each state’s rules," he said.

Santorum, former House Speaker Newt Gingrich and Texas Rep. Ron Paul all see possibilities in March. Gingrich and Santorum eye southern states holding primaries and caucuses, where GOP voters tend to be more conservative. Paul is pushing hard in caucus states.

Beeson says he's unworried. "Governor Romney is the only candidate prepared to compete in simultaneous contests across the country," he said.

"Speaker Gingrich’s and Senator Santorum’s campaigns have resource challenges. The remaining February states may not be kind to them, and their hopes for a comeback in March may be very difficult and based on an incomplete understanding of the delegate selection rules."

Just in time for the rest of the caucuses and primaries, trading card manufacturer Upper Deck is releasing "World of Politics" trading cards featuring the presidential contenders: from still-in-the-running President Barack Obama, Mitt Romney, Newt Gingrich, Ron Paul and Rick Santorum to also-rans like Rick Perry and Herman Cain.

The California-based company says nine subjects will be featured in all: "With so much attention around the 2012 election, we thought it was only fitting to produce a set of cards that would help pay tribute to all the highs and lows of this presidential race by capturing the top candidates on cardboard," said Jason Masherah, Upper Deck's marketing veep. The cards will be released Feb. 21.

It's not Obama's first time on a trading card: the trading card company released a caricature of Obama after he won in 2008. 

The Priorities USA Action super PAC and the Service Employees International Union say they're doubling efforts to "educate voters" about what they call the "two-faces" of Mitt Romney and his "unbelievably low 13.9 percent tax rate."

The efforts come in Spanish language radio ads in Florida and Nevada -- two states with large numbers of Hispanic voters. Priorities USA Action launched a new ad today in Tampa and Orlando, and SEIU launched a new ad in Las Vegas and Reno. 

The Romney camp calls the ads a "dishonest smear from President Obama's liberal allies and a desperate attempt to distract from his abysmal record.

"It will do nothing to help the millions of Hispanics who have been hit especially hard as a result of the Obama economy," said campaign spokesman Amanda Henneberg.

The ads highlight the tax rate Romney pays, charging him with "accusing immigrants of coming to this country to look for handouts," while benefitting from a "massive handout

"On the one hand, Romney is a multimillionaire who pays an unfairly low tax rate," the ad says. "But on the other hand, he accuses hard working immigrants of being opportunistic, declaring that they’re just here looking for handouts."

It then plays a clip of Romney saying "A lot of people just come here or come across the border that have no skill, no education, and are looking for, for a free deal."