Tammy Baldwin, on the Edge of Making History Jeffrey Phelps/Associated Press Ms. Baldwin in a debate with Tommy Thompson, at Marquette University last month. THE event held late last month in the penthouse of the lawyers Barry Skovgaard and Marc Wolinsky had all the trappings of a top-flight fund-raiser, with five-star finger foods, four-finger cocktails and three-term senators, as Charles E. Schumer, Democrat of New York, spoke - and everyone else listened. Even the address, 252 Seventh Avenue, had a patina of glamour, being the building where Katie Holmes holed up after dumping Tom Cruise. The only thing missing that evening was the guest of honor, another woman locked in a battle with a powerful man: Tammy Baldwin, the Democratic congresswoman who is running neck and neck with the longtime Republican lion Tommy Thompson for a United States Senate seat in Wisconsin. Scheduled to speak, Ms. Baldwin (who, like the hosts and many of the people in that room, is openly gay) was instead back home to respond to a sharp-elbowed new ad from Mr. Thompson, something that demanded the candidate's presence in Wisconsin, and not amid fawning followers in a Chelsea loft. And it is that just that balancing act - being a loyal, hard-working representative of her home state and an emerging national figure in the gay community - that has Ms. Baldwin, 50, on the edge of making history, and her supporters, including some of nation's most important gay donors, on the edge of their seats. Though a victory by Ms. Baldwin on Tuesday would represent the election of the first openly gay or lesbian person to the Senate, gay groups have been surprisingly low-key about their public support. Fund-raisers have largely been intimate affairs at people's homes; no giant fund-raising galas in gay enclaves like West Hollywood or the Castro in San Francisco. There have been no celebrity onslaughts like those unleashed in the federal court fight against Proposition 8 (California's same-sex marriage ban). And while outside money from everywhere has been gushing in, a mere trickle of staff members from gay groups are showing up in the election's final days. Even a round of reporting phone calls to some of the country's biggest gay groups and activists, most of whom are typically eager to talk about their political support for issues and candidates, were initially greeted with requests to go off the record or speak on background. Gay rights groups, particularly those based outside Wisconsin, seemed to have been careful not to look too involved, concerned that the appearance of outside influence on Lombardi-land politics might be used against Ms. Baldwin, particularly at the last minute. Being out, it would seem, is not a problem. But being from outside Wisconsin could be. Such fears aren't unfounded: candidates in a few other races have seen recent attacks suggesting that national gay groups are trying to push a "radical agenda," though the Wisconsin race, to date, has been largely focused on the economy. Not that any Congressional race is really local anymore. Chad Griffin, the president of the Human Rights Campaign, the largest civil rights organization devoted to gay and lesbian issues and a backer of Ms. Baldwin, said that both she and Mr. Thompson have big-time financial supporters all over the country. But he said the race was not about national issues, per se. "She is the candidate that has captivated the folks in that state," he said. The president and chief executive of the Gay & Lesbian Victory Fund and Institute, Chuck Wolfe, agreed, adding that the 2010 Citizens United case had effectively "nationalized" Senate races. In Wisconsin, he said his group (a nonpartisan organization that works to get gay candidates elected) had raised and spent "seven figures" helping Ms. Baldwin, more than it had ever spent "on any other race." Then, a moment later, he joked, "Mind you, those lines will probably appear in a tweet now." Mr. Wolfe noted that Mr. Thompson, a former governor, has received far more support from deep-pocket conservative groups like Karl Rove's Crossroads, based in Washington, which paid for a recent ad proclaiming "Tommy Thompson governs the Wisconsin way." And indeed, giving by nongay groups, on both sides, has dwarfed money raised by groups like the Victory Fund. For instance, Emily's List, a group that supports Democratic women who favor abortion rights, has raised $4.5 million on Ms. Baldwin's behalf.