Even as Congress is consumed with fiscal cliff negotiations, lobbyists and activists on all sides of the immigration debate are mobilizing their grass roots, staking out policy turf and gearing up for a huge push next year.

Advocates of overhauling the nation’s immigration laws say their messaging includes entreaties to Congress to keep any bill clean. The fear is the legislation could become a “Christmas tree,” larded up with enough pet projects and controversial amendments to sink it. Such a scenario is not lost on overhaul opponents, either.

“Anybody that comes forward with non- germane measures or something that is intended to delay and frustrate the process, we are going to keep our eyes on them,” said Eliseo Medina, secretary-treasurer of the Service Employees International Union, which supports a path to citizenship for illegal immigrants. “They’re buying themselves a lot of trouble in the next election if they stand in the way of real reform.”

A comprehensive rewrite of immigration laws appears to be one of the few opportunities for bipartisan comity in the next Congress. And it’s an issue that many Republicans say their party must take on, especially after Mitt Romney lost the Latino vote by a huge margin.

Medina said his outreach to the Latino community is full time — with ongoing operations in such states as Colorado, Nevada, Florida, Texas and California. The upcoming campaign will include rallies, one-on-one meetings with members of Congress and more specifics that will be announced within 45 days, he said.