HOUSTON — Texas, Montana and 15 other states sued the federal government and immigration agencies in U.S. District Court on Wednesday to try to derail President Barack Obama’s executive action deferring deportation for up to 5 million people, arguing it’s unconstitutional and will worsen the humanitarian crisis on the U.S.-Mexico border.

State officials noted in their filing: “This lawsuit is not about immigration. It is about the rule of law, presidential power and the structural limits of the U.S. Constitution.”

According to Montana Attorney General Tim Fox, the president’s directive “is nothing but an unlawfully adopted legislative rule: an executive decree that requires federal agencies to award legal benefits to individuals whose conduct contradicts the laws enacted by Congress. Montana and the other states involved in this suit believe this is a clear violation of the separation of powers.”

Greg Abbott, Texas’ Republican attorney general and the governor-elect, announced the lawsuit in Austin

“The president is abdicating his responsibility to faithfully enforce laws that were duly enacted by Congress and attempting to rewrite immigration laws, which he has no authority to do,” Abbott said. The president’s actions amount to “executive disregard of the separation of powers,” he said.

The Obama administration says prosecutorial discretion gives the president the power to take such action.

The states’ lawsuit was filed in U.S. District Court for the Southern District of Texas in Brownsville. Defendants include the federal government and the heads of several agencies, including the Department of Homeland Security, U.S. Customs and Border Protection, U.S. Citizenship and Immigration Services and U.S. Immigration and Customs Enforcement.

The states that joined Montana and Texas in the lawsuit are Alabama, Georgia, Idaho, Indiana, Kansas, Louisiana, Maine, Mississippi, Nebraska, North Carolina, South Carolina, South Dakota, Utah, West Virginia and Wisconsin.

Earlier Wednesday, Texas Gov. Rick Perry called for increased support from Washington for border security, saying in a statement that Obama’s executive action could spark another “mass migration.”

In the wake of an immigrant influx of more than 68,000 unaccompanied children across the border this year — many via Texas’ Rio Grande Valley — Perry ordered a surge of state law enforcement and the National Guard.

Although the number of immigrants caught crossing Texas’ southern border illegally has plummeted 73 percent since June, state lawmakers this week extended the law enforcement surge through August. On Wednesday, Perry ordered state agencies to use the E-Verify system to screen employee eligibility.

“Texas’ increased law enforcement presence in the border region is all the more necessary as the federal government continues to ignore the very real issue of border security in favor of political posturing on immigration,” Perry said. “Without border security, immigration reform is a fruitless exercise.”