The Obama administration’s decision this week to ease visa requirements for hundreds of thousands of illegal immigrants represents its latest move to reshape immigration through executive action, even as the White House gears up for an uncertain political fight over a far-more-sweeping legislative package in the months ahead.

Immigration advocates on Thursday hailed a rule change at the Department of Homeland Security that would make it easier for many undocumented immigrants to stay in the United States as they seek permanent residency, saying it will improve the lives of relatives who could have been separated for years without the changes.

For President Obama — who has called the inability to achieve comprehensive immigration reform among the biggest regrets of his first term — the new policy is among a series of steps his administration has taken over the past year aimed in part at easing the pace of deportations, which have surged during his tenure. Many of the steps came amid a presidential campaign that included sharp disagreements over immigration policy and strong support among Latinos and Asians for Obama.

The centerpiece was Obama’s decision, announced last June, to stop deporting people who were brought to the country as children and have gone on to be productive and otherwise law-abiding residents.

“He is checking off every administrative box he can of what he can do with executive authority that comports with his overall view of immigration policy,” said Angela Kelley, an analyst at the Center for American Progress, a liberal think tank allied with the White House.

The latest policy change is focused on illegal immigrants who have a spouse, parent or child with U.S. citizenship. Currently, in order to become legal they must leave the United States and apply for a waiver forgiving their unlawful presence in the country. Only then can they apply for an immigrant visa. And if they don’t get a waiver, they are barred from returning to the United States for up to 10 years, depending on the case.

The specter of being barred deterred many from applying. But under the rule change finalized Wednesday, those who qualify will be able to apply for waivers from within the United States starting March 4. Applicants must return to their native country for a brief period for the consular immigrant visa process.

The new rule greatly reduces the risk inherent in applying for a waiver, as people whose applications are rejected would still be in the United States when they heard the news. Even for those whose applications are approved, the new rule will allow them to spend much less time outside the United States, as they will travel abroad with waivers in hand.

Michelle Escobar, 38, a U.S. citizen who lives in Laurel, said her husband, German, 33, plans to apply for a waiver under the new rule. Until now, she said, he had been afraid to go to his native El Salvador to apply.

“He would be barred for 10 years, probably,” said Escobar, a state investigator. “That’s why we’ve been so scared to put in for it.”

But champions of stricter immigration controls denounced the administration’s action, saying that such rule changes reward lawbreakers and allow them to cut the line in front of people who have abided by legal procedures.

“It’s definitely using executive authority or privileges to make an end run around the law the way it’s written,” said Jessica Vaughan of the Washington-based Center for Immigration Studies. “The law was intended to make it difficult for people who were living here illegally. This is a way for the administration to change a law that they don’t like . . . without having to go through Congress, where they probably couldn’t get it changed.”

She added: “With each instance of this, the administration is providing amnesty to another group of people, and as long as they can get away with it, they’ll keep doing it.”

Obama has faced sharp criticism from progressives for his administration’s high levels of deportations, which reached 409,849 from October 2011 through September 2012, the fourth consecutive fiscal year that the number increased. But immigration advocates have cheered his policy moves over the past year, and he won reelection in November with more than 70 percent of the Latino and Asian vote.

In another recent policy change, the U.S. Immigration and Customs Enforcement office announced last month that it would focus community detention efforts on illegal immigrants with a record of previous felony convictions or several misdemeanors. Agency officials said the move was made to put the department’s limited resources to better use in targeting the most dangerous criminals.

Still, administration officials emphasize that such administrative actions are not intended as a substitute for broader legislation, which would be aimed at providing a path to citizenship for the nation’s 11 million undocumented workers.

“At the end of the day, those are just crumbs,” Kelley said of the executive moves.

Although Obama has pledged to push for comprehensive legislation early in his second term, the White House’s timetable has been complicated by the prospect of another round of fiscal negotiations over the debt ceiling in February and the president’s pledge to support a gun-control bill in the wake of the mass school shooting in Newtown, Conn.

Both of those issues are likely to embroil the White House in bitter, time-consuming political battles with Republicans, particularly in the GOP-controlled House. Advocates said they are hopeful that Republicans will respond more favorably to immigration reform because the party is eager to broaden its appeal to minority groups in the wake of Obama’s election victory.

Frank Sharry, executive director of America’s Voice, which promotes immigration reform, said the administration’s decision to begin implementing immigration changes last year marked a “turning point.” Obama had appeared to give up on the issue after Republicans gained control of the House in the 2010 midterm elections, and many White House aides were “scared to death” about reviving the topic last year, he said.

The moves “not only rallied Latinos and progressives but won the favor of swing voters and threw Republicans on the defensive,” Sharry said. “It was such a turning point last year that it has turned the old conventional wisdom on its head. All of a sudden Obama was getting kudos for the political moves.”

Analysts said the latest policy change could alter the personal calculus of many immigrants who have concluded that remaining in the United States illegally is less risky than applying for a visa and being separated for years on end.

To qualify, an applicant must be inadmissible only on account of his or her unlawful presence in the United States and must demonstrate that being separated from family would mean “extreme hardship” for his or her U.S. relative.

“It’s a potentially significant feature of immigration law going forward because it removes this Catch-22 that people were subject to before,” said Audrey Singer, a senior fellow at the Brookings Institution who focuses on immigration.

Escobar, whose husband owns a landscaping company, said that barring his return to the United States would be devastating for her family, which includes her daughter, 14, and the couple’s 7-year-old son.

“I wouldn’t be able to afford our rent — we’d lose our home. I’d probably have to move back in with my mother. The children would have to change schools,” she said. “Their sense of security would be completely destroyed.”