TROY, MICH. - Whether Mitt Romney wins or loses the Michigan and Arizona primaries Tuesday, his advisers are warning donors and other supporters to prepare for a longer, more bruising and more expensive fight for the Republican presidential nomination, which may not be settled until at least May.

That campaign trail reality is prompting a new round of intensified fundraising by his financial team, which had hoped by this point to be collecting money for a general election match with President Obama. The campaign is increasingly trying to quell anxiety among Republican leaders, while intently focusing on the mechanics of accumulating delegates needed to secure the nomination.

Romney's aides said they were confident that their sustained attacks portraying Rick Santorum as a Washington insider, and Santorum's shaky debate performance on Wednesday, had blunted their rival's recent surge in Michigan.

But Romney is by no means in the clear, they said, as he fights to avert a loss in the state where he was born and raised -- and where he was expected to handily win less than three weeks ago, before Santorum scored surprise triumphs in Colorado, Minnesota and Missouri.

Prelude to Super Tuesday

Santorum is likewise preparing to fight on for weeks or months, enticed by new party rules that award delegates in early primaries and caucuses based on each candidate's share of the votes. "The race is going to go a long time," he vowed Saturday.

Associated Press, Star Tribune
Jim Wilson, a supporter of Republican presidential candidate, former Massachusetts Gov. Mitt Romney, lashes American flags to the back of his pickup truck before Romney speaks at the Ingham Lincoln Day Breakfast in Lansing, Mich., Saturday, Feb. 25, 2012.

Still, for many Republicans, the question is not just whether Romney will eventually capture the nomination, but at what cost? There is a growing sense among party leaders that continued attacks by the candidates and their allies could damage the party's prospects in the fall.

Reflecting the unsettled outlook, aides to both Romney and Santorum are playing down the importance of the Michigan and Arizona primaries. Those contests are preludes to the biggest day of voting in the Republican campaign on March 6, with 10 states at play on Super Tuesday.

That terrain is far less hospitable to Romney than Michigan and Arizona, particularly a swath of Southern states, where polls suggest that he is trailing Santorum and Newt Gingrich. Gingrich is aggressively trying to revive his candidacy on Super Tuesday in Georgia, the state he represented in Congress, and a super PAC supporting Santorum is advertising across Ohio, another Super Tuesday state.

Playing to the south

The better-financed super PAC that supports Romney, Restore Our Future, is already running ads attacking Santorum and Gingrich in Super Tuesday states. A senior official with the group said the intent was to "kill any comeback talk" in the event of major March 6 victories by either -- or both -- of them.

An early glimpse into Romney's strategy for the Southern contests ahead will come on Sunday when he takes a brief detour from Michigan to attend the Daytona 500 in Florida. Advisers hope that images of Romney mingling with NASCAR fans at the speedway will circulate widely through Southern states as well as in Michigan.

Republican leaders and party activists said they were still alarmed that Romney was struggling to connect with conservative voters. But supporters dismissed the worries.

"Too many people look at this as a sprint," said Saul Anuzis, a member of the Republican National Committee from Michigan and a supporter of Romney. "It's a lot closer to being a game of 'Survivor,' with who can put together a national network to win across the country."