DESTIN -- If Republican Connie Mack IV is shouldering the burden of his party’s control of the U.S. Senate, you wouldn’t know it last week as he finished a six-day bus tour of 17 cities in north and central Florida.

In 26 stops, Mack drew modest crowds and meager media attention as he crisscrossed the state. The steady drip of negative poll numbers had him battling expectations as much as barbs from his challenger, incumbent Democrat Sen. Bill Nelson. And with about four weeks before early voting begins, the general public still seems ambivalent.

In the Republican stronghold of Destin on Thursday, Mack greeted about 25 supporters outside the Donut Hole café on Highway 98, and then went inside to introduce himself to customers.

“Could you get us menus?’’ one elderly couple asked Mack, 45, the four-term congressman from Fort Myers, after he shook their hands. The congressman obliged.

None of it has cracked Mack’s cool.

He has tethered his fortunes, his message and his strategy to Republican presidential candidate Mitt Romney and confidently tells audiences “if Mitt Romney wins, I win. If I win, Mitt Romney wins.”

That’s a hard hill to climb, according to the polls. In this must-win swing state for Romney, the former Massachusetts governor remains locked in a statistical tie with President Barack Obama. The latest Senate polls show Mack trailing Nelson by between nine and 14 percentage points. Even Mack’s own poll, a survey of 600 voters taken last Sunday, showed him five percentage points down, with a margin of error of plus or minus four percent.

“Stay tuned,’’ Mack told reporters in Pensacola Thursday. “We’re not done yet.”

True, and Mack argues he will have enough money and outside help to fight to Nov. 6. He won’t reveal his totals, but predicted there will be "$25 to $30 million" spent on his campaign before it’s over and points to a new infusion of third-party attack ads against Nelson.

The U.S. Chamber of Commerce is spending $2 million on ads this week, Mack said. American Crossroads, a super PAC founded by Republican political strategist Karl Rove, announced it’s spending $1.8 million in Florida on a television ad hitting Nelson’s record on Medicare.

Time is running out, however, with Washington pundits losing interest in what they once viewed as a competitive race. Jennifer Duffy, who tracks U.S. Senate races for the Cook Political Report, wrote in the National Journal last week that the chances of Republicans taking Senate seats from Democrats in Missouri, Ohio and Florida are “remote, at best.”

Mack and Republicans still see Nelson, who is seeking his third term, as vulnerable to a challenge in Florida’s divided political climate. With Nelson keeping a low-profile so far, Mack has attacked with taunts of “Where is Bill Nelson?”

Nelson has agreed to a single debate against Mack in Fort Lauderdale on Oct. 17 and he has scheduled a “Barnstorming Tour” of the state to follow. He raised more than $13 million by the end of the last reporting period in July and steered it toward a barrage of negative television ads, attacking Mack for his personal financial woes, his divorce, his hard-partying youth and attendance record in Congress.