(image Credit: Bill Pugliano/Getty Images)

Mitt Romney had a great Tuesday night , trouncing Rick Santorum in Arizona and winning a nail-biter in his native state of Michigan, but while his victories have solidified his front-runner status and averted all-out panic within his party, next week's  Super Tuesday  is not shaping up so well for the former Massachusetts governor.

No one can deny that Romney delivered in Michigan, where he absolutely positively had to win. A loss would have been nothing short of devastating for his campaign. Instead of a clamor among Republicans for another candidate such as  New Jersey Gov. Chris Christie,  Indiana Gov. Mitch Daniels   or   Mississippi Gov. Haley Barbour   to jump into the race, all the talk today is about Romney's firewall standing firm - yet again. He won in New Hampshire after losing in Iowa. He won in Florida after losing in South Carolina. And  he won in Michigan - and Maine - after losing a trio of states to Santorum earlier this month.

"That whoosh you hear is Mitt Romney and his entire campaign exhaling," ABC News anchor George Stephanopoulos said Tuesday. "This is a huge night for this campaign. He has now won the most contests, he has won the most delegates, he has the biggest organization, the most money. What this has done tonight … is kill any talk in Republican circles about finding another white knight to come into the campaign. [It has]  put Mitt Romney back in a commanding position to get this nomination."

In his victory speech Tuesday night, Romney sounded more relieved than triumphant. "We didn't win by a lot," he said, "but we won by enough." In other words, it wasn't easy, it wasn't pretty, but it goes into the win column all the same.

Maybe that reaction stemmed in some small way from one unmistakable, undeniable fact: Romney had to call on the full arsenal of his campaign operation just to defeat Santorum - yes, the same Rick Santorum who in 2006 suffered the worst loss by an incumbent senator in the nation's history - in his home state, the state his father governed for six years. If it was such a close, tense race in his own backyard, what will it be like on Super Tuesday, when the race shifts south, where Romney will encounter more conservative voters … and no home-field advantage ?

The answer, it seems, is: a heck of a lot tougher. In Michigan, very conservative voters favored Santorum by 14 points. That group makes up 39 percent of the Republican primary electorate in Oklahoma, 38 percent in Tennessee and 32 percent in Georgia -  three of the four most-coveted Super Tuesday states. Combined with the fourth - Ohio - those states hold 243 delegates. If Romney stands a shot at winning any of them, his best bet appears to be the Buckeye State, which has  a smaller percentage of evangelicals and very conservative voters.

But Romney is currently trailing Santorum by 7 points in Ohio, according to the latest Quinnipiac University poll. Aside from his 3.2 percentage point victory in his native Michigan, Romney has lost every other Midwestern state in the primary to Santorum. And Santorum hails from neighboring Pennsylvania, making Romney's task in Ohio even tougher.

The campaigns are already shelling out millions of dollars in Ohio, with Romney's war chest yet again coming to his rescue. Romney's campaign and his allies - led by the Restore Our Future PAC - have reportedly spent a total of nearly $3.4 million there, compared with a total of $527,000 for Santorum and his PAC. Romney's relentless attacks on his rivals have paid dividends so  far. In Florida, desperate to defeat a surging Gingrich, Romney's PAC spent nearly $14 million, most of it on negative ads about the former House speaker. Ditto for Michigan. In Ohio, it's  lather, rinse, repeat.

According to ABC News political analyst Matthew Dowd, Romney still needs to prove that he can put together "a winning streak of states [for] the first time, [that] he can win/unite conservatives going forward  and [that he] can enunciate a positive message that can win states and rehab his image before the fall."

Romney may have a hard time accomplishing that first goal - a winning streak - even before Super Tuesday begins. In Washington state, which holds its caucuses on March 3, Santorum currently leads in the polls. To achieve the second goal, Romney will need to sway the same type of very conservative voters and evangelicals who so far have preferred Santorum - a tall order, even more so in Southern states. And before he can embark on the third goal - outlining a positive message and rehabbing his image - Romney will have to feel confident enough in his chances of securing the GOP nomination to scale back his attacks.

Unaffiliated Republican strategist Carlos Curbelo saw the Michigan and Arizona wins as a positive for the Republican party.

"Yesterday's results offer some hope to those of us that are anxious to begin focusing on the President's record," Curbelo said. "If Governor Romney has a strong Super Tuesday, a lot of this distracting background noise will go away and Republicans can begin addressing crucial swing voters. The longer we remain englufed in this intra-party war, the better for President Obama and his allies."

Craig Robinson of The Iowa Republican does not see Romney wrapping up the nomination anytime soon.

"For the race to be essentially over after Super Tuesday, Romney would have to dominate his opponents for the next two weeks," Robinson said last week. "I don't think that's very likely, but it could happen."

"The only way that Romney can become the inevitable nominee is if he stops losing," he added. "I don't think it's going to be easy for him in Ohio, Oklahoma or Tennessee. He has to win a southern state to essentially kill Santorum and Gingrich."

At the same time, Robinson cautioned, a loss to Santorum in Ohio on Super Tuesday would "severely wound" Romney, while losses in Georgia and Tennessee could create "a narrative that Romney can't win Southern states, [which] would be very damaging."

But with a strong showing on Super Tuesday, Romney could take a big step toward  once again establishing himself as "the inevitable nominee." He looks to be a shoo-in to win in four other Super Tuesday states: Massachusetts, Vermont, Virginia and Idaho. And all that stands between him and the nomination now is a weakened Santorum, a bruised and battered Gingrich  and a winless Ron Paul.

It won't be easy, but victory, it seems, is once again within Romney's reach.

Matthew Jaffe is covering the 2012 campaign for ABC News and Univision.