BOSTON/NEW YORK (Reuters) - Supporters of U.S. presidential candidates Donald Trump and Bernie Sanders may inhabit opposite ends of the political spectrum, but they have one thing in common: an unprecedented hunger for campaign swag. Fans of the Republican billionaire Trump and of Democrat Sanders have bought nearly $20 million worth of campaign hats, T-shirts, bumper stickers, and other merchandise so far, according to campaign officials, a level that political brand experts reckon is a record for a presidential election. The sales reveal deep passion for the White House contenders among some voters, and could also signify an expansion of merchandise as a fundraising tool in future races, said Laura Ries, president of branding consultancy Ries & Ries. “I’m sure we’ll see more of this. Merchandise is a great way of getting your message out there, of engaging people, and of raising money,” she said. Among offerings from Trump, now the only candidate left in the Republican race, are T-shirts featuring slogans like “Team Trump” and “New York Values”, trucker hats emblazed with “Make America Great Again” and a “presidential dog raglan” sweater designed to be worn by dogs. The campaign shop for Sanders, who describes himself as a Democratic socialist and who has promised to go after Wall Street and redress social inequalities, features “Feel the Bern” mugs, T-shirts with slogans like “Join the political revolution NOW”, and a “Babies for Bernie” baby bib. Hillary Clinton, who is expected to fend off the challenge from Sanders to become the Democratic nominee for the Nov. 8 election, has run a much smaller campaign merchandise business. “Hillary is a huge front-runner in the polls, but in terms of passion, she’s lagging,” Ries said. “Not as many people want to wear a Clinton T-shirt.” T-SHIRTS AND COFFEE MUGS The Sanders campaign has raised about $12.8 million in gross revenue from campaign merchandise sales, accounting for some 7 percent of total individual contributions so far, according to Kenneth Pennington, the campaign’s digital director. He said the campaign had sold more than 800,000 individual items since launching last year, including 207,000 t-shirts and 44,000 coffee mugs. That gear cost the campaign $8.5 million to manufacture, representing about 5 percent of the campaign’s total expenditures to date, according to federal disclosures, meaning the campaign’s net revenue on merchandise is about $4.3 million. The primary manufacturer of the goods was Tigereye Promotions of Ohio. Campaign reports do not require candidates to break out revenue from merchandise sales. Trump’s merchandise business is smaller than Sanders’, but still historically huge. The real estate developer has mainly used his own funds to finance his White House bid so far, but his campaign has raised more than $6 million in gross revenue by selling Trump trademark gifts and apparel, representing “a majority” of the campaign’s individual contributions, according to spokeswoman Hope Hicks.  “The sale of official campaign products has been extremely successful,” she said. That gear cost the campaign more than $4.7 million to produce. Among the most used manufacturers were Cali-Fame of California and Ace Specialties of Louisiana, according to federal campaign finance disclosures. The owner of Ace Specialties, Christl Mahfouz, is on the board of Trump’s son’s foundation, the Eric Trump Foundation, which raises money for terminally ill children. Clinton’s campaign, meanwhile, has spent just $1.4 million on swag manufacturing so far, according to campaign records. A campaign official was not immediately available to comment on how much the campaign had raised through the sale of that merchandise. “For Hillary, I suspect we will see more swag, as she tries to pick up Bernie supporters in the general election,” said Karen Post, a brand consultant and author of “Brand Turnaround”. “What young person do you know who doesn’t love T shirts?” The Trump and Sanders swag spending this year is unmatched by recent elections.  Democratic President Barack Obama, seen as one of the best-branded presidential candidates in recent U.S. history, spent just $1.3 million on T-shirts, posters and bumper stickers during his first election bid in 2008, when he galvanized supporters behind his core messages of hope and change slogan and his rising sun campaign logo.  Obama spent less than $70,000 on merchandise during his 2012 re-election bid against Republican Mitt Romney, whose campaign dished out $3.4 million on campaign promotional items, according to campaign finance reports. 