WASHINGTON — Rancor over immigration escalated Friday after President Obama, speaking halfway around the world, promised to go through with a controversial executive order that would shield as many as 5 million undocumented immigrants from deportation and to act before a new Republican Senate can take over.

Obama repeated that he would issue an executive order by the end of the year and promised not to back down over Republican threats that taking unilateral action would cripple future cooperation.

“They have the ability to fix the system,” said Obama during a trip to Yangon, Myanmar. “What they don’t have the ability to do is to expect me to stand by with a broken system in perpetuity.”

Confident that Obama will soon issue the executive order, supporters have begun developing an infrastructure to help qualifying immigrants. They’re lining up attorneys around the country, setting up a hotline and creating a website where vetted information about necessary requirements for the order and instructions could be shared.

They expect the Obama order would grant work permits to millions of undocumented immigrants, loosening requirements of Obama’s 2012 executive order that shielded more than 500,000 young immigrants brought to the country illegally as children. It also could include the parents of children who are U.S. citizens.

“I think that they have signaled pretty clearly that it is going to be based on the number of years that someone has been here,” said Angela Maria Kelley, vice president of immigration policy at the Center for American Progress.

Despite all the talk of cooperation and openness with a new incoming Congress, the prospects of a major bipartisan agreement on immigration appeared remote.

Democrats have rallied around the president in support of a “bold and meaningful” immigration overhaul. In a letter to Obama released Thursday, 116 House of Representatives Democrats said Republican leaders have proven they won’t pass a comprehensive immigration overhaul.

“By failing to do their job – and repeatedly interfering with your efforts to do your job – congressional Republicans threaten to take our immigration system hostage and preserve a status quo that everyone agrees is unacceptable,” the letter said.

While Republicans were united in their opposition, the party was divided over how to confront Obama.

Rep. Matt Salmon, R-Ariz., said Friday that nobody wants a government shutdown. He indicated that Republicans would try to attack whatever Obama does on immigration through the budget process. He said he’d like to see language in upcoming legislation to fund the federal government beyond Dec. 11 that would prevent Obama from using federal money on the executive action.

Salmon wrote a letter with more than 60 Republicans pressing the House Appropriations Committee to include language in the spending bill that prohibits funding for an executive order.

House Speaker John Boehner, R-Ohio, said Thursday that “all options are on the table” to block executive action.