As one of the party's most prominent defense hawks, the Republican from Alpine passes most conservative ideological litmus tests on issues such as national security, taxes, abortion and same-sex marriage.

But as a newcomer to national politics, Hunter needs to raise tens of millions of dollars over the next year to boost his profile among conservative activists, say experienced political hands. That effort could be complicated by the opposition of influential power brokers because of Hunter's long history of opposing free-trade deals and promoting tough border security policies.

“We just had an election where Lou Dobbs' candidates on immigration ended up all over the floor – dead,” said Grover Norquist, president of Americans for Tax Reform, a free-market advocacy group, referring to the populist CNN commentator. “I tend to think it is fool's gold.”

Other top Republicans decry what they consider Hunter's indifferent record on the effort to curb extravagant federal spending.

“Our (political action committee) would cross him off the list,” said David Keating, executive director of the fiscally conservative Club for Growth. “We wouldn't even consider endorsing him because his record on fiscal issues has been so bad.”

In assessing congressional voting records on federal spending, the conservative National Taxpayers Union awarded Hunter an “A” grade in 1993, the first year of the Clinton administration, and a “B+” in 2001, President Bush's first year in office.

His rating then started to slide, to a “C+.”

However, Hunter's situation is far from unique. Virtually every potential Republican presidential hopeful finds himself at odds with some key conservative interest group. Witness Massachusetts Gov. Mitt Romney's problems with social conservatives because of his support for gay rights.

Conservative activists, GOP political operatives and experts on primary election politics say there is an opening on the right for somebody to carry the banner against such candidates as Arizona Sen. John McCain and Rudolph Giuliani, the former New York mayor who assumed quasi-heroic stature after the Sept. 11, 2001, terrorist attacks. Both are generally considered outside the conservative mainstream on many key issues.

Political experts say Hunter should view his campaign as an extended audition for the role of conservative alternative, with an emphasis on his hawkish views on national defense and border security.

“(Hunter) needs a unique selling proposition. He needs an issue that's all his own, and that's tough to do,” said Jack Pitney, a political scientist at Claremont McKenna College with experience as a Republican policy adviser.

Steven Smith, who runs a public-policy think tank at Washington University in St. Louis, said: “The Republican Party right now is fractionated. It's broken down into little purist groups. . . . They're all looking for a champion of their cause. And so the question is, what cause is it Hunter can champion?”

Hunter's skepticism about trade and his aggressive stance on immigration could be a building block for a candidacy that exploits simmering anxieties about globalization among some conservatives.

In his early outings since announcing his interest in a presidential candidacy, Hunter has blasted China for cheating the United States on trade deals to use American dollars to finance a threatening military buildup.

“There is a niche for that,” said Richard Land, who is attuned to the views of Christian conservatives in his role as president of the Ethics and Religious Liberty Commission of the Southern Baptist Convention. “I've got to tell you that his talk about trade will play well among some social-conservative constituencies. It will play very well.”

Opposition to free trade was a key plank in commentator Pat Buchanan's campaigns for the Republican presidential nomination in 1992 and 1996.

Both candidacies ultimately fizzled, most notably during the 1996 primary in South Carolina, when Buchanan finished a distant second behind Sen. Bob Dole of Kansas, the eventual nominee.

Buchanan and his strategists thought his trade protectionism would be a hit with voters in a state whose textile industries have been ravaged by cheap imports. But South Carolina by then had rebounded economically by becoming a strong magnet for foreign investors attracted by America's open markets.

“Within the conservative movement there is a protectionist camp, but I don't think it is a majority,” said David Keene, chairman of the American Conservative Union. “That is a divisive issue within the movement itself, and Duncan is one of the leaders of the nationalist, populist, protectionist standpoint, which gets him strong support within that group. The question is, how big is that group? That is not an unalloyed asset in terms of his makeup as a candidate.”

Joe Gaylord, a GOP consultant, observed, “He can learn from the Buchanan experience that there is a nerve you can touch with (opposition to free trade), but it doesn't go deeply.”

As one of the main congressional sponsors of legislation toughening border security, Hunter may be poised to press the immigration hot button in hopes of cashing in politically on voter unease over a growing community of illegal immigrants, which now numbers about 12 million.

Many Republican conservatives are unhappy with McCain's support for legislation that would provide many of those immigrants a pathway to citizenship, noted William Mayer, an expert on presidential politics at Northeastern University.

“There actually is among Republican primary voters a pretty strong sentiment toward restricting immigration. . . . I think that stuff will play well,” Mayer said.

Patrick Drinan, a political scientist at the University of San Diego, said: “A lot of it depends on whether the conservative movement itself more broadly congeals around a consensus candidate. In the absence of that, you can almost say Duncan Hunter has a good shot at either the presidential nomination or a vice-presidential nomination.”