Karina Velasco paid her way through college by cleaning office buildings in downtown Washington for five hours every evening. She did her schoolwork after getting home at midnight, and is on track to receive her degree in social work next spring.

Karina is a model citizen except for one thing. She's an illegal immigrant. She crossed the border without papers from her home in Mexico 10 years ago, when she was 14.

Under a program initiated by President Obama in 2012, Karina is one of about 550,000 young people, sometimes called "DREAMers," who qualify for "deferred action" regarding their immigration status. That means they can obtain a work permit, a driver's license, a social security number and some assurance that they won't be deported.

Karina can now work for a social service agency that helps other young people deal with the mental side effects of illegal immigration: stress, depression, fear. She knows the symptoms because she suffered them herself.

"One night I woke up with a nightmare -- my mom and dad were being deported," she recalls. "I was crying and crying and I called my mother. I was like, 'tell me you're OK, tell me you're here. What am I going to do with my brother here by myself? Who am I going to turn to?' It was something I was always thinking about."

Karina's terrors have abated, but she knows her protected status is not guaranteed. Obama's program could be canceled by a Republican president.

"I am always living with the uncertainty of what will happen," she says. "I am scared that in a future day I won't be able to renew my deferred action, and I will be in limbo again."

Last week, House Republicans passed a bill repealing the deferred action initiative. That measure will die in the Democratic-controlled Senate, but it's a stark reminder that Karina's concerns are justified. Only 11 GOP Congressmen opposed the bill while 212 supported it -- a clear sign that most Republicans badly misunderstand DREAMers like Karina and what they mean to this country.

Most of them are givers, not takers. They work hard, often at menial jobs -- like cleaning office buildings -- that few native-born Americans are willing to do. They pay taxes. They obey the law. They contribute to their communities. Karina's brightest dream is buying her mother a house.

Voting to plunge these youngsters back into the nightmare of anxiety is an act of mean-spirited vindictiveness. Republicans will pay a price with Latino voters -- and they should.

Critics argue that deferred action is responsible for the flood of children crossing the southern border from Central America. But as Roque Planas reports in the Huffington Post, "there's virtually no evidence to support this increasingly popular conservative talking point."

For one thing, the program only applies to immigrants who arrived before June 15, 2007. For another, rising street violence and political instability spurred the influx of children a year before the deferred action program began.

"The fact of the matter is that all the elements were in place for a large-scale movement of Central American kids across the border, with or without (deferred action)," Planas writes.

Republicans also maintain that by authorizing deferred action, Obama is somehow abusing his executive powers. But as Seth Hoy of the American Immigration Council notes, the president "did not create a new law, sign an executive order or grant anyone citizenship or amnesty." All he did was direct immigration officials to "exercise discretion" in enforcing existing law, "an action that is well within his power as president."

Even the Republican Speaker, John Boehner, concedes there are "numerous steps" the president could take on immigration "without the need for Congressional action."

Obama genuinely hoped for a bipartisan deal on immigration, and the Senate did pass a comprehensive reform package with 14 Republican votes. But House leaders, bullied by a hardline tea party faction, buried the measure.

Frustrated by that intransigence, the president is now considering broader initiatives on his own. One idea would enable parents of DREAMers like Karina to qualify for deferred action; another would extend the program to parents of U.S. citizens.

Normally we don't think executive actions are a good idea. Big problems should command a consensus and be resolved through the legislative process.

But that process has failed.

Millions of lives are in limbo. Many DREAMers and their parents want to be good Americans and deserve to live here without the constant threat of deportation. The president should act quickly to dispel their fears.