A group of Immigrations and Customs Enforcement agents filed a lawsuit against their own agency Thursday, arguing that the Obama administration is not letting them fully identify and deport illegal immigrants.

Secretary of Homeland Security Janet Napolitano says her department does not have the manpower or money to deport the 11 million illegal immigrants in the USA, so she issued a memorandum last year ordering immigration officials to focus their efforts on dangerous illegal immigrants. In June, Obama announced a program that will allow up to 1.7 million illegal immigrants brought to the USA as children to have deportations deferred for at least two years.

The 10 ICE agents suing Napolitano and ICE Director John Morton say those directives violate the Constitution and federal immigration law. "We are federal law enforcement officers who are being ordered to break the law," said Chris Crane, an ICE agent and president of the National Immigration and Customs Enforcement Council, a union for ICE employees. "This directive puts ICE agents and officers in a horrible position."

ICE spokesman Ross Feinstein did not comment on the lawsuit but said more than half of the nearly 400,000 illegal immigrants deported in 2011 had been convicted of crimes, the largest number in the agency's history. He said that shows the decision to focus on the most dangerous illegal immigrants is a policy that works, and June's decision to defer deportation for young illegal immigrants enhances that strategy.

A spokesman for Republican presidential candidate Mitt Romney said Obama may have overstepped his authority by ordering the deportation deferments, and Romney would forge a long-term solution with Congress instead of relying on Obama's "stop-gap measure."

"The courts will have to sort this out, but this kind of uncertainty is unacceptable as these young people brought here as children are seeking clarity on their long-term status," spokesman Ryan Williams said.

The lawsuit, filed Thursday in a Dallas federal court, requests that a judge strike down the two directives and protect the agents from any retribution for their lawsuit.

The suit is funded by NumbersUSA, a group that proposes lower levels of legal and illegal immigration, and the attorney is Kris Kobach, the secretary of State of Kansas who has helped Arizona and Alabama craft strict anti-illegal-immigration laws. His work on this lawsuit is not part of his official state duties.

The lawsuit was supported by some GOP legislators who have criticized Obama's immigration plans as "backdoor amnesty."

"These agent's mission is to keep our borders secure, but the head of their agency is directing them otherwise, telling them to undermine their missions and contradict immigration law," Sen. David Vitter, R-La.

Rep. Luis Gutierrez, D-Ill., said the program actually helps ICE officials by allowing them to focus on the most dangerous illegal immigrants. "Deferred action is a major boost to law enforcement who do not have to waste time on honor students and can do the harder work of actually tracking down and deporting criminals," he said.