Some immigrants in New York City’s Little Colombia may be changing their vote to Republican this year as a result of the Democratic candidates’ opposition to a free trade agreement with Colombia.

Although only a small slice of the electorate, Colombian immigrants in Queens are backing away in particular from Senator Clinton, a candidate who only a few months ago they ardently, and almost unanimously, supported. Even those who are against the deal are switching their allegiance — to Senator Obama, whom they view as a stronger opponent of free trade.

A Democratic Party committeeman for the 39th District in Queens, Orlando Tobon, who is also often called the mayor of Little Colombia, said he had always been a loyal Clinton supporter until this week, after one of her top campaign aides, who had been lobbying for the free trade deal on behalf of the Colombian government, abruptly quit.

In the past few weeks, Mrs. Clinton has sought to distance herself from the proposal to open trade with Colombia as she woos blue-collar voters ahead of the Pennsylvania primary, and in general during the campaign she has become increasingly opposed to free trade deals such as the North American Free Trade Agreement.

In response, Mr. Tobon, a supporter of the Colombia trade plan, said he and his fellow countrymen have been given no choice but to hold their noses and vote Republican in the November election.

“I tell all of our paisanos, free trade with America is like opening a store we can sell to with 300 million customers. We think it’s very important,” Mr. Tobon said.

“We’ve supported Hillary Clinton, and we can’t understand why she’s not supporting us,” he added.

He said the issue had been the main topic of discussion for days at his tax preparation agency, which also acts as an informal town meeting hall for the Colombians and other Hispanic immigrants who congregate along Roosevelt Avenue in Queens.

In New York’s primary, Mrs. Clinton trounced Senator Obama in these heavily Hispanic neighborhoods in western Queens. That support hadn’t waned even as she lost her position as the campaign’s front-runner. About a month ago, a day-long informal survey of voters in Jackson Heights and Corona, many of them Colombians, didn’t turn up any Hispanic voters who said they wouldn’t have voted for Mrs. Clinton again if given the chance.

Yesterday, however, not a single Clinton supporter — or at least any willing to admit it — was to be found among a dozen Colombians interviewed.

There were nearly half a million Colombians residing in America in 2000, according to Census data, with more than 77,000 and as many as 115,000 living in New York City.

Mr. Tobon’s reasoning in favor of the trade deal has caught on with Mauricio Palacios, 28, who works at a funeral preparation business next door to Mr. Tobon’s office. After repeating Mr. Tobon’s example of the store with 300 million customers, Mr. Palacios said he had decided that Mrs. Clinton had “never been a friend of Colombia.” He now supports Senator McCain, the presumptive Republican nominee.

Lucy Martinez, who works with Mr. Palacios at the funeral business, said she is keeping her voting plans a secret, but nodded as her co-worker listed reasons why Mr. McCain would be better for their home country.

Other Colombians argue that the trade deal could be disastrous. They point to some of their newest neighbors in Jackson Heights and Corona: immigrants from Mexico who say they left home after free trade made it harder for farmers to compete with cheap American products.

Despite Mrs. Clinton’s opposition to the deal, several former Clinton administration officials have been directly involved in advocating on behalf of the Colombian government, including Mrs. Clinton’s former campaign adviser, Mark Penn, who stepped down after his involvement became public.

“It was bad for the Mexicans. The big supermarkets are going to come and the little stores will close,” Marino Carmona, 50, said. Two older women standing nearby clucked their approval of his assessment. Then, 30-year-old German Villara jumped into the conversation.

“I was going to vote for Hillary, but now I’m going to vote for Obama,” he said.

At a clothing boutique across the way from Mr. Tobon’s agency called Made In Colombia, 18-year-old Mariana Puerto said she saw the free trade deal as way to open up opportunities at home so young people like herself wouldn’t have to leave.

Although she can’t vote, Ms. Puerto said almost everyone she knows has abandoned Mrs. Clinton over the trade deal.

“I’ve changed my mind about her,” she said. “I think other people are changing, too.”