THEIR CONSTITUENCIES GARY BAUER: Targets social conservatives with his anti-abortion stance and admonitions for stronger morality in the country and tougher discipline in schools. He is running as a Reagan Republican, calling for less government and lower taxes. Aides say his work with local organizers of conservative groups could pay off in Iowa, but the polls have not reflected that. The biggest groups of financial contributors have been retirees and health professionals. BILL BRADLEY: Bradley has criticized Vice President Al Gore's targeting of constituency groups, but what helped trigger that strategy was Bradley's aggressive appeals to groups like gays with positions that were openly supportive of their stance on issues, while Gore took a more centrist -- and cautious -- approach. Bradley's health care plan also aims at key Democratic groups, low-income people, blue-collar workers those in service jobs -- that currently have trouble getting full health coverage. Bradley is most competitive with Gore among wealthier Democrats, men and those with more education. Lawyers were the biggest contributors to Bradley's campaign, followed by those in the securities and investment business, according to campaign finance records. GEORGE W. BUSH: Focuses on a broad range of voters, getting support from conservatives hungry for a winner and reaching out for moderates and even traditionally Democratic groups. His support in the national polls has been strong overall, usually in the 60s, and relatively strong across the board. His biggest groups of contributors have been retirees and lawyers, followed by those in the real estate business. STEVE FORBES: Has identified key leaders in conservative groups, farmers, home schoolers, property rights people, small business owners in Iowa. The Forbes campaign has developed detailed databases of these leaders, and has had more success courting them in Iowa, which has a more stable population than New Hampshire. Forbes biggest group of contributors has been retirees, those in the securities and investment business, followed by other types of financiers. AL GORE: Has aggressively pursued traditional Democratic constituency groups such as blacks, women and the elderly as the nomination race grew tighter, bringing a reminder from party moderates recently that aligning too closely with liberal interest groups could be a formula for defeat. Gore campaign spokesman Chris Lehane says Gore is offering the same broad message on areas like the economy that he's offered for the last seven years and will appeal to a broad audience. But Lehane also noted that it's essential to solidify support among the core Democratic constituencies. Gore has stronger support than Bradley among blacks, women and those with less education and lower incomes. Lawyers and law firms also had contributed the most to the Gore campaign, followed by retirees and those in the real estate business. ORRIN HATCH: Targets a broad range of Republicans, not focusing as much on specific groups. So far, the campaign has not been making much of a mark in the polls. His biggest financial supporters have been lawyers, followed by lobbyists. ALAN KEYES: Has been targeting social conservatives as well as conservatives in general with a message of the nation's fading morality and less government intervention. The biggest groups of Keyes contributors have been retirees and health professionals. JOHN MCCAIN: Focuses on reform-minded conservatives, independents, military veterans and those fed up with Washington. His strongest support in the polls has come from older people and men. His biggest groups of contributors have been retirees and those in the securities and investment business.

WASHINGTON -- Gay attorney Charlie Spiegel says that when the Democratic presidential candidates voiced opposition to an anti-gay marriage proposal in California, members of the homosexual community took notice -- and opened their wallets.

"It's the kind of thing that energizes people," Spiegel said, noting that he sent a check to Al Gore and his domestic partner sent one to Bill Bradley. "The first thing that happened was they were writing checks to both of those candidates."

Now Bradley and Vice President Gore are competing for their votes with calls to let homosexuals serve openly in the military. Spiegel says the call for an end to discrimination is a mainstream position, not an appeal to the fringe.

While Democrats are reaching out to gays and blacks -- key constituencies -- the Republican presidential candidates are tailoring their messages to appeal to conservatives who oppose abortion and value tax cuts.

As the first votes of campaign 2000 approach, candidates are sharpening their appeals to core constituencies -- a short-term necessity with long-term risks.

Gore, the Democratic front-runner, and Texas Gov. George W. Bush, the Republican leader, began their campaigns by aiming at the broad middle of the electorate. Each now faces strong challenges, particularly in New Hampshire, from Bradley and Sen. John McCain, respectively.

The potential pitfalls of a narrowly targeted approach became clear when Gore said he would insist before appointing anyone to the Joint Chiefs of Staff that they agree with his policy that gays be allowed to serve openly in the military.

Gore later backpedaled to say he meant he would not tolerate officers not following orders. Republicans already have pounced on the Democrats' military-gays debate as evidence that a Democrat would not be suitable as commander in chief.

Bush has proposed a $483 billion, five-year tax package that would spend a large chunk of projected surpluses. A tax cut that size should play well with conservative Republicans, but taxes are not a top issue with other voters.

"For any presidential candidate from either party to succeed, they have to be able to communicate to their own partisans, but at the same time communicate to people who are not partisans," said political scientist Earl Black of Rice University. "Every successful presidential candidate has figured out a way to do that."

Exit polls from the 1996 presidential election show that almost half of the voters identified themselves as moderates, a group that went almost 2-1 for President Clinton. And a fourth of voters identified themselves as independent, voting for Clinton by a 43 percent to 35 percent margin.

Clinton's two victories have helped redefine the winning formula for presidential elections. It was developed by moderate Democrats, including Gore and the Democratic Leadership Council, and is based on crafting a broad message that appeals to the center but can be tailored when necessary to retain the party's base.

"Of course you want to appeal to every constituency," said Al From, president of the DLC, noting that Walter Mondale successfully won Democratic constituencies in 1984 before being soundly defeated by Ronald Reagan. "But today's voters are more informed, more educated, more affluent, more independent, more suburban, less unionized, less urban. With that kind of an electorate, you have to appeal with your ideas."

In addition to debating over health care and education, Bradley and Gore fought hard for organized labor's backing before Gore was endorsed by the AFL-CIO.

Bradley also complains that Gore is playing "constituency politics" when he tells various groups how Bradley's proposed health-care plan would hurt them.

While the support of these groups is important in a Democratic primary, only 23 percent of all voters in November 1996 exit polls said they had a union member in their household. Only 5 percent said they were gay.

Bush has the kind of advantage in the Republican competition -- he has raised more than $67 million and has a big lead in national polls -- that allows him to appeal to a broad audience with a centrist agenda, while he signals conservatives from time to time with a tax-cut proposal or a comment about his Christian faith.

Bush's biggest challenge comes from McCain, who is neck-and-neck with him in New Hampshire and whose style appeals to reform-minded conservatives, independents and military veterans.

Publisher Steve Forbes also has mounted a credible challenge to Bush in Iowa with a well-financed campaign targeting fiscal and social conservatives. Forbes had 18 percent support to Bush's 45 percent in an Iowa Poll this month.

Political veterans say Iowa is the ideal state for coalition-building because of the stable population and clearly identifiable leaders of different voter groups. But a longtime leader of one of those groups says constituency politics is tougher than ever.

Chuck Gifford, a veteran labor leader, recalled when candidates would rely heavily on key organizers in constituency groups spread the word about which presidential candidate had the best positions on issues.

"It made you a power broker," he said in a recent interview. "There used to be a significant number who would follow the pied piper. Now there's just too many people who aren't willing to go down that road."