A group of 20 Republican Senators, including Minority Leader Mitch McConnell (Ky.), wrote to President Barack Obama on Tuesday, questioning his authority to stop deporting illegal immigrants who arrived as children and seeking documents relating to the policy change, as well as answers to a raft of questions.

“Please provide copies of any documentation, including any and all legal opinions, memoranda, and emails, that discuss any authority you have or do not have to undertake this immigration directive,” the Senators wrote.

The communique came in response to Obama’s June 15 announcement that the government will no longer seek to deport illegal immigrants under age 30 who were brought to the United States before they turned 16 and have been in the country for at least five continuous years.

“Given that this directive is effective immediately and that many questions remain unanswered, we ask that you make available Department of Homeland Security Secretary Janet Napolitano, U.S. Immigration and Customs Enforcement Director John Morton and U.S. Citizenship and Immigration Service Director Alejandro Mayorkas to respond to our concerns,” the Senators wrote. The lawmakers asked for responses and relevant documentation no later than July 3.

The letter, also signed by Senate Judiciary ranking member Charles Grassley (R-Iowa), asks whether Obama consulted with attorneys on his legal authority prior to the announcement and whether he obtained an opinion from the Office of Legal Counsel or anyone else in the administration.

The Senators note in the letter that Obama a year ago made statements indicating that he did not have the authority to carry out such an initiative.

“Why has your position on the legal authority of the Executive Branch changed,” the lawmakers wrote.

Along with questioning the authority, the Senators also voiced frustration over the president’s willingness to go around Congress.

“Your recently announced directive runs contrary to that responsibility,” the Senators wrote. “Not only is your directive an affront to our system of representative government and the legislative process, but it is an inappropriate use of executive power.”

The letter also seeks answers to a host of other questions about the policy, including what will happen if the decision is challenged in court and why the cut-off age is 30 if the goal is to help students. It also asks about the fate of young, undocumented immigrants if a challenge to the policy is upheld.

Other questions had to do with the cost of the policy.

“Can you assure us that the total implementation cost of the program will be paid for by the individuals seeking benefit, or will U.S. taxpayers subsidize any part of the program?” the Senators asked.

The letter argues that granting work permits to those eligible for the program could make it harder for American citizens to find work.

“Your directive runs count to the premise that American workers must come before foreign nationals,” the lawmakers wrote. “It’s astonishing that you would grant work authorizations to illegal immigrants during this time of record unemployment.”