Meet Harry Rubenstein and Larry Bird — National Museum of American History curators and longtime hunting buddies. Their prey: campaign buttons and quirky convention hats.

Every four years, armed with black portfolios and press credentials — “There are no credentials for museum curators,” Bird noted — the bespectacled duo scours the halls and floors of the presidential conventions in search of the quintessential campaign trinket or rare political ornament.

The Smithsonian has dispatched curators to the party conventions since 1964, and actively has sought campaign memorabilia since the 1950s.

“If we could just bottle the whole convention … and put it in a drawer, we would,” Rubenstein said. “Since we can’t do that, what we have to do is look for those things we think are expressive of it and that people will find useful in the future.”

Earlier this year, Rubenstein and Bird also made an appearance at the New Hampshire primary to collect at least one item from each presidential campaign — before the candidates began dropping out.

After a brief reprieve from the Democratic confab in Boston, the two 53-year-olds returned to the hunt this week at Madison Square Garden’s GOP gathering. Look for Rubenstein and Bird trolling the Manhattan pavement in search of items from street vendors — and even protesters — related to the convention experience, as well as scoping out the GOP’s officially sanctioned memorabilia offerings at the Grand Old marketPlace in the New York Hilton.

Their best finds typically reflect an individual’s personal attempt to stake a claim, in some small way, on the political process.

“You always hope for a certain level of activism and engagement that’s experienced materially” by convention attendees, said Bird. “That can happen. It’s kind of like love.”

Yet the same level of personal investment that makes an item desirable also can complicate efforts to obtain it. “Many times what you can’t collect [is] something that means so much to the person it’s really not fair to even ask them for it,” Bird said, such as a papier mâché pineapple hat worn by some Ohioans at the 1996 GOP convention in San Diego.

To get a specimen of the Bob Dole-inspired headwear, “I talked one off a delegate,” he said.

When such on-the-spot requests are rejected, the two whip out the most potent tool of persuasion they possess — a business card with the magic name of their employer.

People “have called back to the Smithsonian to see is it really true that this person works for the Smithsonian, and then they offer it,” Rubenstein said.

At July’s Democratic National Convention, the pair netted roughly 100 items, ranging from “canned” campaign standards such as Kerry/Edwards signs and buttons to more novel effects such as a talking prescription bottle and a fluorescent-yellow “Labor’s Back” vest. They are still waiting to hear if the Smithsonian will be the destination of the Massachusetts delegation’s floor sign, Bird said last week.

The duo tries to collect at least one state delegation floor sign from each convention, and thanks to an agreement with the Maryland delegation — who “guarded” the sign until the two were able to take it down — they managed to salvage the Old Line State’s marker, Rubenstein said.

Rubenstein said it’s impossible to rank his favorite items, saying, “It’s the sum of the parts.” Still, he conceded, “For 10 minutes I would say this ‘Give Bush a pink slip’ [scarf] was my favorite.”

Meanwhile, Bird held up an unadorned, rectangular red sign with a blue back. “This was used during the roll call of states by the Texas delegation. It was to turn Texas from a red state to a blue state. I thought that was great. At last they got it down to a poster with no writing. I wanted to meet the person who came up with that.”

Once a convention concludes, Rubenstein and Bird “weed out” duplicates, then catalogue the items, which are mostly archived in the museum’s fourth floor political history storage space.

Altogether, the 4,000-square-foot, climate-controlled room houses about 90,000 artifacts, including the brass and copper buttons made to be worn at the time of George Washington’s first inaugural, as well as pencils topped with the head of 1928 Democratic nominee Al Smith and plate-sized “I like Ike” buttons.

“It’s not a collection of record, but it’s the closest thing to a collection of record for the national political campaign process,” Bird said.

Midway down an aisle of nondescript white metal storage units, Bird stopped to point out one particularly significant cache.

“This is our national pen, pencil and swizzle stick collection,” he joked, pulling out a drawer teeming with such curiosities as a PT boat pen from John F. Kennedy’s 1960 presidential campaign.

“Probably now it should be a Swift boat,” Bird laughed.