For months, immigrant advocacy groups like the Chelsea Collaborative and Berkshire Immigrant Center have been gearing up to push lawmakers on state and federal immigration reforms. They’ve held statewide forums, marched in Washington, D.C., and organized rallies with hopes of seeing the major immigration overhaul promised by Gov. Deval Patrick and President Barack Obama. But after the historic election victory of Republican Scott Brown to the U.S. Senate, those illusions may be evaporating. Political observers say Brown, who ran on a platform opposing some of those reforms, has emboldened conservative voters, and they will likely table reforms in the near future.

“Much of the angry and frustration of voters, particularly those on the right, are clearly aligned with forces that oppose immigration reform,” said Paul Watanabe, a political science professor at University of Massachusetts-Boston. “They are vocal opponents of anything other than enforcement.” Watanabe said it’s now doubtful that Patrick and state lawmakers will spend political capital pushing any controversial proposals in an election year shortly after Brown’s victory. Patrick has said he is planning to seek re-election this fall, but is struggling with sagging poll numbers.

During his campaign, Brown said he opposed granting driver’s licenses and in-state tuition rates to illegal immigrants — ideas Patrick vowed to support in November after receiving recommendations from an advisory panel. As a state senator, Brown also introduced legislation that would have required proof of citizenship or right to work in the U.S. for wage enforcement cases. “His record is concerning,” said Eva Millona, executive director of the Massachusetts Immigrants & Refugee Advocacy Coalition, a group that represents 130 immigrant groups.

But Brown’s positions excited conservative voters and won him endorsements and praise from national groups like Americans for Legal Immigration PAC, who hailed him for opposing “amnesty.” It’s a dramatic shift from positions taken by his predecessor, the late Sen. Edward Kennedy. The Democratic senator sponsored a 1965 immigration law that changed the nation’s demographic makeup by scrapping an immigration quota system that favored Western Europeans, and he remained for decades a “go-to” legislator for immigrant advocates.

After Brown’s victory over Democrat Martha Coakley, the Federation of American Immigration Reform, or FAIR, sent out a statement arguing that Brown’s win showed even Massachusetts voters oppose some of Kennedy’s ideas on immigration and that it would be “suicide” for any politician to support certain reforms. “If support for amnesty and benefits for illegal aliens won’t fly in Massachusetts, it won’t fly anywhere,” said FAIR president Dan Stein. “Democrat or Republican, any candidate who ’leans into’ amnesty in 2010, as some advocates advise, is likely to share Martha Coakley’s fate.”

Massachusetts is home to around 1 million foreign-born residents, or 14 percent of the state’s population.

For their part, immigrant advocates in Massachusetts say they aren’t giving up on prospects for state and federal immigration reform. But Millona acknowledged, after Brown’s win, “It makes it harder for us.”

Still, Millona said advocates hope to meet with Brown soon. “In the state Senate, Mr. Brown did not always support issues that were important for immigrant communities,” Millona said. “But the sober responsibility he demonstrated in his victory speech was very promising, as was his humble recognition that he has a lot to learn.”