PHOENIX (Reuters) – US Hispanics, frustrated that President Barack Obama has yet to fulfil a pledge to revamp the immigration system, are warning him to deliver this year or face the consequences in congressional elections in November.

Tens of thousands of Latinos plan to rally in Washington tomorrow, cautioning that their support for Obama and his fellow Democrats, who face a struggle to hold their majorities in both houses of Congress, hinges on the issue.

But the event may be overshadowed by a vote that day in the House of Representatives on healthcare overhaul legislation that would be Obama’s signature achievement so far.

Obama benefited in 2008 from a huge turnout of Hispanics, drawn by his promise to deliver immigration reform allowing millions of illegal immigrants a path to citizenship.

But that has been slowed by Obama’s yearlong push for healthcare reform, efforts to revive the slumping economy and resistance in Congress after an immigration overhaul was torpedoed in 2007 under Republican President George W Bush.

With November elections looming, analysts say time is running out to tackle the issue this year.

While Hispanics are seen as unlikely to switch support to Republicans, who have fought immigration reform without a clampdown on illegal immigrants, they could hurt Democrats by failing to turn out at the polls.

“We are still interested in seeing the Democrats succeed, and see Mr Obama succeed,” said Jorge-Mario Cabrera, of the Coalition for Humane Immigrant Rights of Los Angeles, which is sending delegates to the march.

“However, we also are telling Congress and the president that this particular promise is so essential to our community’s well-being, to our families’ well-being, to our nation’s well-being, that if it’s not kept, we will remember in the November elections,“ he said.

Immigration is a bitterly-fought issue in the United States where some 10.8 million illegal immigrants live and work in the shadows and where Hispanics, the largest immigrant group, are a rapidly increasing voting bloc.

Supporters of an overhaul say illegal immigrants fill the jobs that Americans are not willing to do, while opponents say they drive down wages and are a drain on government resources.