Teresa Valcarce, a.k.a. the Portrait Lady, with a painting of Bernardo de Galvez, a Spanish hero of the American Revolution, which she successfully fought to have mounted in the U.S. Capitol. (Bill O'Leary/The Washington Post)

Sometimes Congress takes a while to keep its promises.

This one took only 231 years.

It has been that long since Congress pledged to hang a portrait in the U.S. Capitol honoring Bernardo de Galvez, a daring Spanish military leader who became a hero in the colonies during the American Revolution. The story of that ancient promise and how it is — ever so quietly — finally being kept is really the story of the Portrait Lady.

It’s a story of how one of Washington’s least powerful people — an effervescent labor-union secretary — got its most powerful institution to step up.

The Portrait Lady’s name is Teresa Valcarce. She’s a 45-year-old mother of three who commutes to downtown Washington from Bethesda. Before moving to the United States a decade and a half ago, she worked the information counter at the airport in her home town of Malaga, Spain.

In a city defined by org-charts, she’s acutely aware of her place — she calls herself a “tiny, tiny, truly tiny fish” in a voice that sounds more Andalusia than K Street. And yet she seems incapable of grasping the implicit social contract of the org-chart: that the little fish don’t get a say.

Three years ago, when her mother sent her an article from Spain mentioning the unfulfilled promise about the Galvez portrait, her reaction was both practical and naive. “I work down the street from the Congress,” she declared. “I’ll just go down there and tell them to put it up.”

In a sense, Valcarce was picking up a fallen baton. In 2010, another Spaniard had made a discovery at the National Archives that thrilled the small world of Galvez enthusiasts. (Yes, there is a world of Galvez enthusiasts. We checked.) It was a May 1783 letter from Elias Boudinot, the president of the Continental Congress, to an American revolutionary financier, Oliver Pollock. In the letter, Boudinot accepted Pollock’s gift of a portrait of Galvez.

Galvez had been the governor of Spanish-controlled Louisiana. He earned the enduring appreciation of the American revolutionaries by not only defeating the British in Florida but also by allowing colonial troops access to the Mississippi River as a critical supply line. There’s a statue of him near the State Department. The city of Galveston, Tex., got its name from him, and St. Bernard Parish in Louisiana is a nod in his honor to his patron saint. But his American Revolution heroics have been largely lost to time and overshadowed by the feats of, say, the Marquis de Lafayette, a Frenchman who fought with the colonial forces and was a pal of George Washington’s.

The discovery of the Galvez portrait letter prompted a brief spasm of excitement. The Bernardo de Galvez Cultural Association in Malaga sent word to Spanish diplomats in Washington about their native son. Nothing happened.

This made no sense to Valcarce. “This is America,” she said of her adopted country. “We keep our promises. This is the legacy for my children.”

A wedge into the Capitol

She started calling the office of the official Senate historian. She called and called. She called so much that the staffers took to calling her the Portrait Lady. “They are so cute!” recalled Valcarce, toggling between Spanish and English, every bit the pert persuader with a flower tucked behind her ear. “So sweet.”

The historians dug up a congressional resolution from 1783 ordering the portrait to be “placed in the room in which Congress meets.” She was more convinced than ever.

But how to get it done? By now, she’d essentially turned over all her free time to researching the portrait and getting historians, expats and anyone else who would listen fired up about it. She had buttonholed law professors to get their thoughts on legal preced­ents; she had jawboned archivists. But she needed a wedge into the Capitol.

She got it last April when a Spanish television crew arrived in Washington to film an episode of a popular program, “Espanoles en el Mundo,” about Spaniards who live abroad. One of the segments followed a Spanish-born newspaperman as he conducted an interview with Rep. Chris Van Hollen (D-Md.). Valcarce tagged along; she was sort of like a stowaway. When the interview ended, she cornered Van Hollen.

“Mr. Congressman,” she said, grasping his hand. “You’re not going to believe this, but I need you to fulfill a 231-year-old promise.” Van Hollen’s office followed up with her almost immediately.

But things stalled in the House, and she shifted to the Senate. During a function at the Spanish ambassador’s residence in January, she pulled aside Sen. Robert Menendez (D-N.J.), a Cuban-American whose ancestors came from northern Spain.

“This is big,” she told Menendez.

Menendez and his staff were intrigued by Valcarce’s pitch. “It’s hard to say no to her,” Menendez said with a chuckle in an interview. “She’s charming and tenacious.”

Even though Menendez is the chairman of the high-powered Senate Foreign Relations Committee, it’s not like he can just walk over to a wall — even in his own committee room — and start pounding nails.

“Nothing is ever that easy,” Menendez said.

Once Valcarce had made it into the building, she was subject to its frenetic rhythms. One evening a Menendez staffer told her that she needed more letters of support. And she needed them by the next day, when a big meeting was scheduled to woo the Senate curator’s office — no easy task. “They hate influence,” Menendez deadpanned.

By noon the next day, Valcarce had managed to acquire testimonials from groups she’d never even heard of, a collection of associations and societies and clubs, including a beach museum in Florida, an association that called itself the “Granaderos” — or grenadiers — of Galvez and a genealogical society in Bexar, Tex.

The goal was a bit more modest than it was when Valcarce began her quest. The 1783 resolution could be read as suggesting that the painting be hung in one of the chambers where either the full House or Senate meets. The advocates now aimed for the seemingly more attainable, but still daunting, goal of getting it into a committee room in the Capitol.

‘I need a portrait’

In the midst of all this, Valcarce had an alarming thought. She had been spending all her time lobbying for a portrait to be hung. But she was missing one key thing: a portrait.

No one could point Valcarce to the original Galvez portrait or tell her whether it had ever been delivered — or whether it had even existed, for that matter. Valcarce had searched for it in Philadelphia and New York, following the trail of the Continental Congress. She had even tracked down some Boudinot experts in his home state of New Jersey. Nothing.

She called Manuel Olmedo Checa, the Galvez association member in Malaga who unearthed the 1783 letter.

“Manuel, I’m going to need a portrait!” she said.

Since Manuel knows everything about Galvez, he knew that a portrait with an impressive provenance was kept in a private collection in Malaga. That painting had reputedly been commissioned by the Spanish king to honor Galvez after his return from the Americas. A well-known Spanish artist, Carlos Monserrate, offered to copy the portrait as a donation.

And so it was that in June, Valcarce received a lushly brushed oil painting, roughly 3 feet by 4 feet, of Bernardo de Galvez, posed in an elegantly embroidered suit with a medal pinned to his chest. She stashed it for safekeeping with the Daughters of the American Revolution, who had become enthusiastic supporters. It stayed there until just a few days ago, when a crew hung it on the west wall of S-116, a compact but ornate room decorated in rich golds and reds that the Senate Foreign Relations Committee uses to mark up bills and to host official coffees with heads of state.

Tentative plans are being made for a public unveiling sometime next month, so the portrait hanging has been hush-hush. The Portrait Lady dreams of Spain’s monarch, King Felipe VI, coming for the unveiling, or at least posing in front of the painting one day.

“Oh, my God!” she said. “He needs to come. I’m going to call him.”

At this point, who could doubt her?