In a sea of gray — gray hair, gray suits, gray expressions — Rosario Marin is something else.

Dressed in a smart pink skirt and dark blue blazer with military epaulets, she faces a hotel ballroom full of bankers with a warm smile. She may be the only Latina in the room.

Marin is the treasurer of the United States, so her visit last week to the American Community Bankers’ conference in Washington, D.C., is hardly unusual. But while other speeches are laden with banking jargon or dry references to fiscal policy, Marin’s is one sunny platitude after another.

“In America,” she says, “if an immigrant can rise to become its treasurer, anything is possible.”

Surely she is the only speaker to tell the bankers that day: “I want you to hold my hand, because we’re all in this together.”

It is easy to see why Rosario Marin is now the latest in a long line of Republicans mentioned as possible challengers to Sen. Barbara Boxer (D-Calif.) in 2004. Because the line is a lot like the roomful of bankers: In a sea of grays, Rosario Marin is something else.

“For California Republicans, it’s either retreads, celebrities or promising new political stars like Rosario Marin,” says Fernando Guerra, director of the Center for the Study of Los Angeles at Loyola Marymount University.

Guerra, who has followed Marin’s career since she was elected to the Huntington Park, Calif., City Council in 1994, says Golden State political observers “are taking talk of her possible candidacy seriously for two reasons — one, her profile, who she is, and two, the lack of a Republican bench.”

The question, though, is what is fueling the talk of a Marin for Senate campaign just now — and whether Marin herself is taking it seriously.

“I’m just flattered,” is all she’ll say of the newfound attention.

This much is known: While Marin’s name has quietly been included in the mix of possible Republican Senate contenders since late last fall, the buzz intensified after she gave a fiery — and partisan — speech at the California GOP convention last month.

“Some Democrats claim Miguel Estrada is not Latino enough,” news accounts reported Marin saying of President Bush’s embattled judicial nominee. “Give me a break.”

Talk of a candidacy reached its peak 10 days ago with two plugs from pundit Robert Novak, one in his syndicated column and another on CNN’s “Inside Politics.”

Privately, some Republican operatives say Marin’s prominence at the GOP convention was no accident, and Republican leaders on both coasts are now quick to talk up the 44-year-old treasurer’s potential.

“We know she’s being mentioned as a candidate, and she’d be an outstanding candidate and an outstanding Senator,” says Dan Allen, communications director of the National Republican Senatorial Committee.

But for all the laudatory talk about Marin, there is little evidence that key Bush political lieutenants or well-connected California GOP financiers are orchestrating the boomlet. There have been no carefully leaked and skillfully placed stories in California newspapers the way there have been in other states where the Bush political team is promoting a specific Senate candidate. There haven’t been any highly publicized secret meetings between the highest-ranking Latina in the Bush administration and Karl Rove.

Asked after the bankers’ conference whether she has talked to Republican leaders about running for the Senate and what they have been telling her, Marin says those are good questions and politely turns to leave the hotel. A Treasury Department spokesman says she is unavailable for interviews about politics.

All the White House will say officially about Marin, through spokesman Dan Nelson, is: “The president is very pleased with Rosario Marin’s service and the leadership she has provided to the Hispanic community.”

One national Republican fundraiser, speaking on the condition of anonymity, says the national GOP believes California is a lost cause.

“You either need a self-funder there or a superstar who is going to generate enough enthusiasm to draw a lot of money,” the fundraiser says. “[Marin] isn’t that.”

And yet, as California Republicans argue that they can deny Boxer a third term only if they find the perfect challenger, the talk about Marin persists. A moderate woman or a Latino, some GOP strategists believe, would have a far better chance in a statewide race than some of the other names being mentioned as candidates, like Reps. Darrell Issa, Doug Ose and George Radanovich, or businessman Bill Simon, the unsuccessful Republican candidate for governor last year.

Democrats, however, take a different view.

“This is all part of a very routine and predictable cycle in which the Republicans are saying that Barbara Boxer is going to be very hard to beat, so let’s go beyond the same predictable names and throw out a few new names,” says Roy Behr, a consultant with GMMB’s Los Angeles office who works for Boxer.

So who is Rosario Marin and why are some Republicans so high on her?

She came to Southern California from Mexico City at the age of 14, knowing no English. Her father, a factory worker back home, could find work only as a janitor.

“We faced an enormous amount of hurdles,” Marin says.

Because of her language deficiency, Marin was found to have an IQ of 27 when she entered high school — far below the benchmark for mental retardation. Three years later, she graduated with honors, went to work in a Beverly Hills bank, in her words, “as an assistant to the receptionist,” and put herself through college while working her way up through the bank hierarchy.

Sixteen years ago, after marrying an immigrant from Nicaragua who works for the Los Angeles city government, Marin gave birth to a son with Down’s Syndrome. From that point on, she became a prominent and vocal activist in California on behalf of children with disabilities. She has two younger children without disabilities.

Through her advocacy work, Marin caught the attention of then-California Gov. Pete Wilson (R), who gave her a job in his administration.

In 1994, Marin was elected to the City Council in Huntington Park, a heavily Democratic and Latino city of more than 100,000 southeast of downtown Los Angeles. Guerra, of the Center for the Study of Los Angeles, calls Huntington Park “an amazing place.”

During the nonpartisan elections, Guerra says, Marin soft-pedaled her Republican leanings, but used them to her city’s advantage once she took office.

“Rosario was an incredibly stabilizing force,” he says. “Her relationship with Pete Wilson drew a lot of attention to the city.”

Marin lived modestly, according to newspaper accounts, and frequently walked the community to meet with constituents.

“She connects with people,” Guerra says. “They see a woman who connects with their aspirations. She embodies the Mexican and the Mexican-American dream that you see in California.”

And when Wilson embraced an anti- immigration referendum that had Latinos up in arms, Marin did not suffer politically.

“She had to walk a tightrope,” Guerra says. “She did a very good job of clearly identifying that while she was supportive of the governor, she wasn’t supportive of his policies that adversely affected her community. It was pretty impressive.”

Marin became a leader in the California League of Cities, a regional executive with AT&T and one of the state’s most prominent Latino Republicans. After Bush was elected, he appointed her treasurer in 2001.

The U.S. treasurer oversees the U.S. Mint and Bureau of Engraving and Printing and also signs all paper money, among other duties. Marin has made “financial education” a centerpiece of her tenure, preaching the importance of fiscal planning and the dangers of credit to poorer communities.

“People, unless you tell them over and over and over again, they forget,” she reminds the bankers. “Education has to be constant.”

When she finishes her extemporaneous 20-minute speech, a bank executive from Pennsylvania tells her, “Your passion and enthusiasm are contagious.”

That’s precisely what some consultants see when they ponder the political potential of Marin. That may not be enough to launch a Senate candidacy against Boxer in 2004, but it bears watching in the future.

“I don’t know,” Marin says. “I should have been a cheerleader. I’m always looking at the bright side of things.”