TAMPA, Fla.- New Jersey Gov. Chris Christie used the most important speech of his political career Tuesday to portray Mitt Romney as a Mr. Fix It who would champion tough reforms rather than worry about winning a popularity contest.

The underlying message of Christie's Republican National Convention keynote address to undecided voters: Think with your head and not with your heart.

"I believe we have become paralyzed by our desire to be loved," the brash governor told an enthusiastic crowd on the first night of the convention. "Our leaders today have decided it is more important to be popular, to do what is easy and say 'yes,' rather than to say 'no' when 'no' is what's required. Tonight, we're going to choose respect over love."

The Romney campaign acknowledges that a likability contest with President Obama is a losing proposition. But if voters calculate that they need a CEO rather than a master orator, his camp said, Romney could shake concerns that he doesn't fully connect with voters.

For Republicans, Christie served as the ideal surrogate for such a no-nonsense message. A conservative governor from a blue state -- like Romney, the former governor of Massachusetts -- Christie has risen through Republican ranks thanks to his high-profile battles with public-sector unions in a state where union influence remains strong.

With voters disillusioned by stubbornly high unemployment and mounting debt, Christie said Romney would champion ideas shunned by Democrats and Obama, "who whistle a happy tune while driving us off the fiscal cliff."

"We believe in telling hard-working families the truth about our country's fiscal realities," he said. Democrats "believe that the American people don't want to hear the truth about the extent of our fiscal difficulties and need to be coddled by big government."

However, the confrontational style that has become a Christie trademark was largely missing from the convention's keynote address. Christie focused instead on his blue-collar roots and personal biography, striking a dialed-back tone at a moment when much of the nation was focused on Hurricane Isaac bearing down on Louisiana.

Christie's speech never mentioned Obama by name but referred to "absentee leadership in the White House."

Democrats have broadly attacked Romney's choice of Wisconsin Rep. Paul Ryan as his running mate. But Ryan drafted a Republican budget proposal that drastically slashes spending, cuts taxes and remakes Medicare and that, Christie said, is evidence that the GOP is committed to solving the nation's problems no matter the political cost.

"We win when we make it about what needs to be done; we lose when we play along with their game of scaring and dividing," he said. "Leadership delivers. Leadership counts. Leadership matters."

Democrats were quick to dismiss Christie's self-portrayal as delusional.

"Chris Christie is talking a lot tonight about political courage," said Obama campaign spokesman Danny Kanner. "But Mitt Romney refuses to tell the American people how he'll pay for his $5 trillion in tax cuts weighted toward millionaires and billionaires. That's because he'll either explode the deficit or raise taxes on middle-class families."